In general I have unfortunately never gotten much return on any social media marketing. 

It may take 1-2 years and by the end you will have forced some appreciation from the renovations but also got some natural appreciation from the market.

In southern CA, even garage conversion ADU additions are typically costing more than the value added.  

I would like to find a way to generate additional income and am exploring options other than having a long-term roommate.

I am in the Milwaukee market. 

It’s a market where cash flow is achievable without needing a massive upfront investment.

Texas has additional laws against these options.

The opportunity cost of losing potential market gains in your retirement fund should also be considered.

Quote from @Brendan Jones: For the homes, and or properties that you will use as a primary or a rental property one big thing I look for is infrastructure in the area, extrinsic value (I.e. hospitals in the area, schools, and job market), and the last thing is creature comforts for people (I.e. is a store to get groceries 1 hour away or 2 minutes away).

Did you figure in the cost of the other tenant paying less than market rent until you can get them up to market rent or replace them with another tenant and how long that will take?