the 4 kinds of side businesses you can start

ah, the side hustle. i’ve become somewhat of a (self-proclaimed) expert at doing random things on the side over the course of my life.

in the last few years i’ve created udemy courses, launched a self-published book (under a fake name – not proud of this one), done marketing consulting, launched an email course (with a paid back-end), airbnb’ed my apartment, traded stocks, bought cryptocurrency (my best investment to date), bought a condo and put it on airbnb, wrote a book (a good one), bought a business (and now another one), put affiliate links on my site, given paid talks, written book summaries, and built an affiliate site for a basketball dribbling course i never took (also not proud of this one).

heck, even my current company began as a side project.

and those are just the ones that worked! i’ve tried tons of other things – buying motorcycles on craigslist and flipping them across the bay, buying cars and paying people to use them to drive uber, starting an affiliate site for people with eyebrow dander, starting an email course for people interested in nootropics… the list goes on.

i’ve seen firsthand how freeing it is to make even 1-2k a month on your own.

i still feel that way.

it’s a complete game changer, waking up with more money than you had when you went to sleep. for too long, i’d start my day by refreshing udemy’s instructor dashboard to see how much i’d make. then the traction amazon page to see our sales, then airbnb, then cryptocurrency…

making money via side businesses (or side hustles) gave me the confidence to quit rackspace and go out on my own 4 years ago. having a few thousand a month coming in on autopilot gave me the freedom to charge rich rates as a growth consultant, as i knew i’d be okay if they said no (for the record: they said yes and it worked well for both parties).

through all these experiments i’ve gotten a sense for the kind of side hustles that are doomed to fail, and those that are likely to work.

the biggest key to successful side hustles that i’ve seen? understanding that  neurontin you’re not starting a startup

get this idea out of your head.

you’re starting a profitable side business to bring in cash and build your capability as an entrepreneur. you are not starting the next facebook – just bringing in some cash to buy your freedom.

side hustles can grow and evolve, but to work they need to have a few traits. they need to:

  • solve a problem someone is already aware of
  • give someone something they’re looking for
  • NOT require a lot of maintenance or hand-holding
  • have a no-brainer path to profitability

as far as i’ve thought about it, i think there are 4 ways you can build a successful side hustle:

  1. buy an existing asset
  2. launch a product on a marketplace with existing demand
  3. launch a unique, one of a kind product in a new space where you can buy demand (adwords, facebook, etc.)
  4. arbitrage (craigslist, airbnb, trading, uber)

let’s cover them one at a time.

buy deltasone prednisone 1. buy an existing asset

this one is probably the easiest, and (annoyingly) requires the most money to pull off.

it’s also pretty self explanatory. buying an apartment and renting it out to someone is one of the most common ways to generate income in the US. you buy an existing asset (a house) and it out on a monthly basis. after a few years, you’ll have made your initial money back and the rest is just profit. easy!

real estate is the easiest example, but you can apply this concept (pay a lump sum up front in exchange for regular payments later on) to all kinds of things.

my partner ryan and i did exactly this when we bought fomo. we loved the app, it was growing well and kicking off steady cashflow. so, we bought it.

it’s the way we structured it that’s key. we seller financed the deal, meaning we bought it for an up-front price and made the payments over time. amazing!

we’re now applying the same strategy to other shopify apps via mkay holdings: buy a shopify app up front, enjoy the monthly profits into eternity.

beyond real estate and shopify apps, there are all kinds of existing assets you can buy. i know one guy who found a watercolor tutorial site with a ton of organic traffic. to monetize, the site was showing google ads on the sidebar, and using amazon affiliate links. all told, it was pulling in $500-1000 per month.

my friend then bought the site, developed a paid course around learning to paint watercolor, and was making 10k+ a month in just under 6 months.

i’ve had other acquaintances buy the rights to unpopular songs or jingles and collect on royalties, others who buy youtube channels or instagram accounts, and still others who buy amazon businesses. the list of existing assets you can buy are practically endless, and if you have 1-2 ideas as to how you can improve an asset, you could have a winner on your hands.

even better, with shopify exchange you can now buy existing sites for next to nothing (some sites go for $250) and get some experience building a business.

2. launch a product on a marketplace with existing demand

this is my favorite way to launch a side business: spend time on a marketplace where people are spending money, and figure out how to create a product that people are looking for.

example – a few years ago, my roommate and i ran the 2nd ranked airbnb in san francisco. we were renting out our living room for $250 a night, our entire apartment for $500+ and making a killing.


mainly, by paying close attention to what airbnb wanted. we realized that – from airbnb’s perspective – they want hosts who do a few things:

  1. communicate quickly with potential guests
  2. accepts as many stay requests as possible
  3. gets lots of 5 star reviews
  4. has a listing with great photos and a high conversion rate

a listing with the above qualities is one that will make airbnb the most money.

we created a profile with TONS of photos of our place, the surrounding area, tourist attractions, fun things to do… basically every photo of our area we could add, we did.

next, we asked our potential guests to message us the dates they were thinking of booking BEFORE they booked or submitted a request.

this step allowed us to respond quickly to guests (boosting our #1 criteria) and meant that – as long as we verbally approved the requested dates – we had nearly a 100% rate of accepting booking requests.

just by optimizing these areas, we pretty quickly had a top 3 airbnb in san francisco.

let’s take another example. a few years back, i launched sql for marketers, a udemy course teaching marketers how to use the SQL programming language without learning how to code.

i saw a gap in the market, and had friends making udemy courses and doing well. so, i decided to make my own.

i started by evaluating other courses on the udemy marketplace, and realized that – from udemy’s standpoint – their best courses would be those that:

  1. drew a lot of student registrations
  2. were highly rated
  3. had good student engagement

so, odds are if you create a course that fulfills those conditions, you have a udemy winner on your hands.

some of the courses i’ve made on udemy. to be clear, i’ve spent nearly zero time on any of these since launching my last one in august 2015, hence why monthly revenue is low.


once you recognize what a given platform wants, your job as a side hustler is to fulfill that algorithm’s desires.

i know of friends who’ve given away thousands of free coupons to specific subreddit groups and online marketing forums to boost the number of students in each course. they’ve also paid people to leave positive reviews, and created incentives for people to watch more content.

in any case, the principle stands: if you can find a niche on a marketplace that you think you’ll be able to own with some time, the results can be remarkable. this is the truest side hustle there is, as the marketplace will do the hard work of acquiring and servicing customers for you.

if i were to start another side business now, the platforms i’d look at are:

  • skillshare / udemy
  • ebay / amazon
  • amazon ebooks
  • the shopify app store
  • the google chrome app store
  • any sort of niche marketplace where people buy stuff: wordpress themes, woocommerce themes, etc.
  • airbnb

now get started 🙂

3. launch a unique product in an area where you can buy customers via paid acquisition (adwords, facebook, etc.)

this one is the most similar to building a startup. however, there are a few things that make this different:

  • you want to focus strictly on small niches. not because you don’t want to make money, but because you don’t want to face a ton of competition. the smaller the space, the less likely it is that a larger company launches a similar product, or a VC-backed startup raises $5mm to come after you. not fun.
  • you must be able to acquire customers via paid acquisition: ads on facebook, instagram and google.
  • your product must be unique, or uniquely solve a niche problem that several thousand people have.

great businesses i’ve seen in this category include things like (directory of functional medicine clinicians), journals of all kinds, brennan dunn’s email course, this software app for florists.

when we started kettle & fire, we thought it would fall into this category: niche category where we could build a small, profitable business. as soon as we launched we realized the business was much larger than we could have anticipated *shrug*

that said, doing this with a product is hard. it requires some direct experience with a problem (even a small one), and some creativity + original thinking. the key here is doing something differentiated that’s appealing to a given niche.

a good way to get ideas in this area is to look at niche products that have been successful elsewhere and apply them to a niche you care about.

for example, i’ve noticed over the last few years an explosion of popular daily journals: the five minute journal, daily quotes, 5 year journal, daily stoic, etc.

what if you combined this interest – people want daily journals – with a niche you cared about?

for example, if you created a journal for people just starting a ketogenic diet… one with recipes, challenges, educational material and a community they could turn to for support… would that work?

i don’t know. but i have a hunch it might.

the other iteration i’ve seen work well here is applying your skills to a niche in a way that’s a low time investment but high ROI for your clients.

for example, if you have some expertise in a/b testing, set up and run 1-3 a/b tests for e-commerce or saas businesses a month. charge 1-2k, and give high-level reporting.

this would likely take you 2-3 days of setup per month, and then another 1-2 days to fully report everything. and yet – if you know your stuff – the ROI will almost certainly be there for the company.

in fact, all of my companies pay an agency to do just this model. they run 3-5 a/b tests a month for us, report back and make changes. we pay them 4-5k a month, and always make more than that from the tests. no brainer.

this flavor of side hustle works especially well if you have expertise in something that can make a company more money (i.e. marketing or sales), or expertise in an area where you can save them some serious dough.

p.s. if you’ve read this far and want an idea for a product in this space, hit me up. i have a ton of these small ideas yet no time to do them myself.

4. arbitrages

this one works, but is probably my least favorite of the bunch. it involves finding an arbitrage between two assets and exploiting that for profit.

what do i mean? here’s an example.

a few years ago, i realized there was a arbitrage near san francisco, where i lived. people were selling motorcycles for $2,000 in oakland… and the same bikes would go for $2,500 in san francisco… right across a bridge.

this is clearly an arbitrage opportunity. a bike in oakland is not worth less than the same one in san francisco.

so, there’s the opportunity – buy the bike for $2k in oakland, drive it across the bridge and sell it for $2500. instantly profit $500 with relatively little risk.

similar arbitrages exist everywhere. my roommate for a while was buying toyota prius’s and paying people minimum wage to drive them around taking uber rides. he’d then take the difference between what uber paid him and what he paid his drivers… often 5-10k a month.

there are similar ones with buying goods on craigslist and selling them on eBay/amazon, buying goods wholesale and selling them off on craigslist, or even buying bottled water at costco and selling it by the bottle outside baseball stadiums. all arbitrages.

now, why don’t i love these sorts of side businesses? a few reasons.

first, they tend to become crowded pretty quickly. markets trend towards efficiency, which makes it really hard to consistently have very profitable arbitrage opportunities. in fact, with the motorcycle thing, i suspect a few other people started doing the same thing and i was quickly getting outbid for bikes. not great.

secondly, these sorts of arbitrage opportunities can be rare, which makes them not ideal for a side business (since the income is unpredictable.

lastly, arbitrages can take a lot of time up-front to find, and can go away quickly enough that the up-front investment isn’t worth it. such arbs can be great in the financial world, but not as great in the world of side hustles.


i hope this explanation gave you some good ideas for side businesses you could start.

in the next post, i’ll break down how exactly i tested my idea for kettle & fire before launching it so that i knew it’d work from day 1.

since my $400 test, kettle & fire has since become a multi-million dollar enterprise. and it all started with a quick and dirty mvp test.

i’ll also show you the exact steps i took to move quickly and determine in a short period of time if a side business is going to work.

interested? comment below and let me know if this is something you’d be interested in.


thanks to abram for pushing me to write this, and ryan kulp for unconsciously motivating me as i wrote this at 1am, unable to sleep. 

33 responses

  1. > interested? comment below and let me know if this is something you’d be interested in.

    Yes please

  2. Nice post! I think doing some side hustles is one of the easiest ways to build marketable skills and learn the confidence that you’ll always be able to make some money if you need. I have my current company now that pays way more than my side hustles, but I’m still able to bring in $1-2k per month with pretty passive side businesses. I’m working on getting a duplex now to live in one unit and rent out the other.

    While dabbling in side businesses may seem like a waste of time, it seems like honing skills you can use else where.

    Have you ever hired someone to take on one of your side businesses full-time? I just found a guy to run an affiliate site I have part time to try to turn it into something bigger

    1. Absolutely! I think that’s the preferred route – hire someone to take it on full time.

      1. Cool cool. I kinda mentioned this on Twitter, but would be interested to get a post on how you manage your time between Kettle and Fire, FOMO, Cross-sell, then other experiments you run.

        I know some people split by day or morning/afternoon split, or have you partnered up or hired so well that you simply have weekly check ins on the other stuff that isn’t the main focus?

  3. Love this post, great content. I have been venturing into side hustles lately myself. Nothing too big since money is limited. Maybe you can post some content on how is the best way to start a side hustle on limited cash. I have developed a shopify store and learning all about the different marketing platforms to get traffic and buyers to the store. I am in the process of developing another website for affiliate purposes. I am learning a lot but it takes time and motivation. I am not a big risk taker and skeptical about all the different money making offers on the internet, so this post has helped a lot and I will take a look at all the suggestions made here. I am very interested in how you tested for kettle and fire, and the way in which you knew how it was a good investment before hand. Looking forward to the next post. Continue the great content. Thanks!

  4. It only works if you have that hustle of a con artist and are pushy.

    What about normal people who can’t write a book or sell an app because they don’t know how?

    1. You learn, instead of complaining about how you don’t know something and assuming anyone who starts something is a con artist.

    2. i know Justin, he is not pushy or a “con artist.” conflating selling with being unethical is a sin and you’ll be punished for it in the market.

  5. Great post, thank you.
    I like the idea that you think about the algorithm of the platform and then optimize your listing/course.

  6. Good stuff, very interested in a follow-up post with the things you mentioned 🙂

  7. Awesome post ! Also, very interested in seeing your next post and follow up you mentioned. This was very helpful Justin!

  8. Good stuff! Interested in the next one.

  9. Would love to read the next post! Also, sent you a message about some of your business ideas that you have yet to try!

  10. Hi Justin, great post, definitely keen to hear more from you on this topic…

  11. Hey Justin, came across your content from Nat’s site. Good writing and food for thought here. I definitely want to see the follow up article on how you test your side hustle ideas so consider this my vote.

  12. Absolutely interested in the story of Kettle & Fire. Will be awesome to get a first hand perspective of what your did, what you expected, what happened, how you scaled etc. Thank you.

  13. Great post. Thanks!

  14. Thanks for sharing. I’ve been interested to try out to create apps, but am afraid of tax issues in US. I read somewhere that once you’ve income from the side, all of your income (Including work as an employee) must be filed under self-employment, meaning business & not as personal tax. Is that true? Will appreciate any info on this.

  15. Id love to learn more about your approach to testing and validation.

  16. Great article. I would really like to hear more about your Kettle and Fire start up story.

  17. Great advice! I’m currently working on generating passive income on demand. So far, it has only been about 2 months since I started and I’m already making $500+ a month with just a few hours of work each week.

    If you’re wondering how this possible, check out this webinar where John Crestani shares his $1.5M formula which helped him become a 7 figure marketer.

    This free webinar completely transformed my mindset while showing me how to build an online business from the ground up.

    Watch the replay here:

  18. Great advice! I’m currently working on generating passive income on demand. So far, it has only been about 2 months since I started and I’m already making $500+ a month with just a few hours of work each week.

    If you’re wondering how this possible, check out this webinar where John Crestani shares his $1.5M formula which helped him become a 7 figure marketer.

    This free webinar completely transformed my mindset while showing me how to build an online business from the ground up.

    Watch the replay here:

  19. Очень интересует!!

  20. Please post the Kettle and Fire info

  21. Definitely interested!

  22. Great post! Would love to learn more about Kettle and Fire, are you able to share that follow up post you mentioned?

  23. I would love to hear about your MVP test that launched Kettle & Fire! Great post.

  24. Thanks for sharing such great information with us. I hope you will share some info about Relationship issues. Please keep sharing.

  25. Hey Justin, love this article! Never thought about all the other asset types out there to own other than real estate. I’m currently a rising senior in college, and my internship just got shortened due to Covid-19. As such, I have a lot more time on my hands and am interested in starting a side hustle. I tried hitting you up by following the article links, but it looks outdated. If you have any unique product ideas to share though, I’d love to know!

    1. For sure! Would love to chat – mind emailing me?

  26. Hey Justin! Great post – quick question, where/how did you buy the Shopify app? Was it via a marketplace, or adhoc?

    I’m wondering if there’s something akin to Shopify Exchange for Shopify Apps – and if not, I’m considering building it.. ?

  27. Incredible article distributed here by you. I have long been eager to adapt new things in relation to this topic, and there is no doubt that I have adapted new things today. office for sale

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