This means building a reputation of honesty, reliability and consistency as well as having the ability to work well with others.

Keep on the slow but consistent march and you'll get there!!

I get requests about tax return consistently.

My thoughts are consistent with some of yours....  

Any trouble finding good, long term tenants consistently? 

I faced this same decision twice in the past 6 months, kept both and did the BRRRR with them.  3 main reasons I did this 1) I want to build cash flow and both were in good locations 2) I don't have a consistent enough deal flow to feel confident I can put the money right back to work 3) I didn't need the money from the sales to fund the next deal.I regret having sold every piece of real estate I've ever sold (past primary homes).

Learn your county and state laws, put systems in place to keep consistent marketing going out, and finally become the expert and go to option for sellers.

My humble opinion is that you either need a lot of money or a lot of time to start getting consistent leads when you are starting out.

It is called Craig's List.I don't know of any such commercial platform and would never be an investor on such a platform.The crowdfunding sites provide a variety of services to investors that all cost money.  

This means getting a quality list, sending unique mailers and being consistent with your mailings.