Not what you were looking for but real estate (mostly rental) has been and remains my primary passive income.
There's plenty of "real-estate investing" information online but most of it looks scammy as hell.
EDIT: I'm based in NYC, FWIW
I do agree in reference to fees from brokers etc, but if you do some deals you will find someone you can work with and honestly at that point they'll work with you on the fees and you won't care as much either because they'll take the liability so their fees are fair.
1. 135 hours is a LOT of time to invest for even tens of thousands of dollars return. I could build and market a side project or two in that time, which could have potential for significantly higher return.
2. To recoup that return, I have to take a big risk, using a highly inexperienced agent (me) in a huge dollar transaction where everyone I speak with will have much more experience.
3. Worst decisioning -- if I am my own agent, I'm not in a good environment for optimal decision making.
There are other reasons outside the scope of your question (some people prefer lower touch investments), but those are a few.
The math just doesn't work out, if you get to the point you are doing that many deals, just hire a broker for your business.
Getting access to the MLS isn't that hard. And finding a good agent/broker to work with is very doable as they want to work with investors since it is a source of recurring income usually for them.
That all said, I am always interested in other peoples approach to minimize transaction fees, but most investors I know in real estate use this approach as it just works and minimizes liability.
As far as landlording a small number of properties, most of the knowledge involved is how to be handy, or knowing trustworthy people who are handy. One piece of advice I would offer here is to charge slightly below-market rent to get better tenants, especially if you're an amateur.
And something a lot of people misunderstand is the relationship between appreciation and cash flow. They're inversely related because lots of appreciation attracts more buyers who drive down rental margins by bidding up purchase prices. Rapidly appreciating properties in a place like Seattle may have lower cash flow than you would anticipate given the demand, and properties with very little appreciation in a state like Ohio may have much better cash flow. But as I said, you should buy a local property and just accept the market conditions. If you want to invest in real estate elsewhere just invest in a REIT.
There are lots of classes you can go to. The first thing I'd do is talk to local real estate brokers and ask them about the market and how things are going. Then see if they can introduce you to another investor that is local. Local knowledge is pretty key for real estate. Also, check into local real estate investment groups, the good ones are pretty selective but if you can meet someone on it you might be able to tag along and get some "free" education until you are ready. This is actually how I started way back when.
Townhomes and Condo's are a little different because you will always have a board for those, and I have had some good luck with Condo's but in general I avoid anything where another entity besides the local city/county can dictate what I can or cannot do.
I actually set things up slightly different but essentially it follows the same process. I have service providers I negotiated and setup that manage different aspects for me, so most all I have to do is make an approval or call and I don't have to pay a percentage fee each month. I learned how to do this after I had a bunch of properties in the past and was paying 8-12%/month in fees for each property but all they were doing was making calls on my behalf or setting up service providers to do it. Once I figured that out, I setup all my own service providers once and cut out the management fee. There are even people that cover the stuff like evictions etc as a service so you don't have to be involved on it.
It requires maybe a few hours of my personal time every couple of months as an average.
Plumbing I found through trial and error, and to be fair for any job where I see a bigger repair bill, e.g. > $500 I'll generally get quotes to keep everyone honest. There are exceptions of course, but when I start seeing bigger repairs being requested it sends up some red flags because we maintain everything really tightly.
Our lawn service and our pest service are the same ones we have do all the units and our own home too. We found both of them through a referral and tried them at our home first. Then slowly gave them more.
I actually found out that in many cases my background checks were catching stuff the rental agency did not which really pissed me off. I use the local sheriff's office to run the background for $20, and then credit check with an online company for $15. I get a true picture of the person/people this way, the rental agency wasn't doing a background check, it was only a want/warrant check and credit check. I prefer knowing the background of people and being able to deny for valid concerns, like the one I found out had been evicted from their last 3 places but lied on their application about prior evictions. The real estate company running my old checks would have never seen that since they just did a wants/warrants check, but I did and denied these people the rental for lying on the application about prior evictions. That said, I had a young family rent a house from me one time that had been evicted and gone bankrupt the prior year. They never lied to me, were honest as best I could tell, and upfront with me about everything so I rented to them after meeting with them. I only required them to provide a full months rent as security instead of a reduced amount, which they totally understood. Never had a problem with them and they got their security deposit back cause they took care of everything.
When things to break or need service (usually a few times a year something minor pops up), my involvement is approving a repair or calling on a company I have used prior to take care of it for me. I have service providers for each property that maintain it for small fees, so like lawn, pest, sprinkler, AC is all taken care of on preventative maintenance plans.
I did have one home we sold at a loss because of the housing crash. It sucks, but it also taught me a number of valuable lessons, and really improved my game.
With real-estate, there is a cliche saying, you make the money when you buy the property not when you sell. This is so true. If you buy it right, you will do well, when you buy it wrong it will almost always bite you.
Flipping is an easier place to lose money if you aren't careful. But if you are flipping you aren't doing it for passive income. I do like flipping but it is not passive and in my area has been hard the last few years because of the local market trends.