Look at the demographics of your specific location to see if the rent is within 30--40% of income level. 

When adding the rental income for Unit 2, it asked for % sq.ft. rented out.

A couple of things I would have done differently would have been to keep my W2 income as lonnnnnnnnnnng as possible, like longer than you think. 2nd would be do wholesale or sell more in the start rather than trying to keep everything possible as a rental. 

A significant portion of an agent's expenses is marketing, so by referring people or promoting the agent, you can significantly reduce their expenses, and they may be willing to reduce their fee to you!"

So if you think you can net say $45k/yr in profit it will take you 3 years to break even if you ignore income taxes.

To reduce risks and take advantage of opportunities, modify your investing plan as necessary.Overall, investing in rental properties in the Houston market can be a rewarding venture with the right approach, diligence, and mindset.

I pay 6% interest only on free-and-clear houses, and have also taken over mortgages, subject to the existing financing.A rental ought to be on your tax returns for 2 years before lenders use the extra money as income.  

How can I setup a Solo 401k if I have only rental income?

@Ben Omonira House Hacking is a great way to get into the RE as well as reduce your overhead cost.

Could you go reinvest it in another property to build even more income?