If you're just an individual that buys real estate but makes primary income from another source, just buy good properties off of the MLS and hold on to 'em. 10 years from now, the purchase price doesn't mean much or really change your return.It's like trying to buy/trade stocks rather than index funds.

However, there is such a thing as a self-directed solo 401k plan which is very popular for those who are self employed.Following are the similarities and differences between the solo 401k and the self-directed IRA.The Self-Directed IRA and Solo 401k Similarities Both were created by congress for individuals to save for retirement;Both may be invested in alternative investments such as real estate, precious metals tax liens, promissory notes, private company shares, and stocks and mutual funds, to name a few;Both allow for Roth contributions;Both are subject to prohibited transaction rules;Both are subject to federal taxes at time of distribution;Both allow for checkbook control for placing alternative investments;Both may be invested in annuities;Both are protected from creditors;Both allow for nondeductible contributions;Both are prohibited from investing in assets listed under I.R.C. 408(m); andNeither may be invested in your own business.  

Here in CO there's an additional license required if you're soliciting money from individuals then loan it to others or even just brokering the loans.

In this scenario, you are lending money to yourself as an individual, it allows you to make regular mortgage payments to yourself rather than paying the P+I to a bank or other lender.The first step is to qualify for a Non-Arm’s Length Mortgage with a financial institution. 

I have two units in two different buildings. Both are currently rented out long-term. I am looking to buy a third property in the same market. All other things being equal, is there any benefit to purchasing the third...

Florida already passed an anti-squatter law and the process is faster and simpler:Under HB 621, a property owner can request law enforcement to immediately remove a squatter from their property if the following conditions are met:The individual has unlawfully entered and remains on the property;The individual has been directed to leave the property by the owner but has not done so; andThe individual is not a current or former tenant in a legal dispute.

This can cater to multiple small families or individuals on SNAP, maximizing the utility and affordability of the property.

Contrary to Melanie's awesome performance, most individual RE investors per multiple academic studies do worse by 3-4% per year than the REITs do, and many reasons for this, REITs have access to lower cost of capital, lower property management costs (Realty Income-O-, spends 0.6% a year on all management), and many other reasons, but big problem, REITs as very liquid, then people can buy high and sell low causing poor returns too, as above. 

Partnering with an experienced individual in the space will help build that credibility that you are lacking.

FYI, self closing doors and locks do nothing when you are dealing with an individual intentionally leaving the doors open.