Mostly from my salary, but I also own two SFH which I rent for $1300/month each with mortgages of around $800/month, including taxes and insurance.My goal is to retire by the age of 35 and focus my energy on either owning an apartment complex or commercial real estate.

If you understand a market extremely well that can be a a way of specializing in its own versus investing in one asset class in multiple markets especially because you can leverage one team to manage all the properties and be more efficient in managing one team versus multiple so don'tfeel bad.

For me, the sweet spot between between scales of efficiency and quality tenants has been in duplexes.

If its the latter I'd recommend you focus your time and energy more on analyzing deals.

He also was willing to replace my leaking evaporator coil unit and recharge the unit with an R-22 equivalent (cheaper cost but 3% less cooling efficiency) for $1.2k, so he wasn't just trying to sell a new unit like a few of the other companies we got bids from.

What most people I´ve spoken to do here is just going to networking events, talking to a lot of people and slowly compiling their investor lists, but this is probably not a very efficient way.

It’s for every property type, it’s just simpler in large MF because one efficiency achieved can change your NOI substantially which forces your value higher. 

@John KimMight be a way to structure it more tax efficiently...How big of an acquisition fee are we talking about?

So yeah the more you manage FOR YOUR SELF the more efficient you become.

Of course, doing this type of work will save money at first, but if you are trying to scale, you want to focus your time and energy elsewhere.