I want to increase my portfolio, but not sure if it makes sense.

If using a PM, they are expensive and often bring the return in line with LTR.  2)  STRs and MTRs are at risk of increased regulation.  

I am reaching a point where I am starting to build up some cash, so I am looking into ways I can invest it and increase my cashflow for years to come!

It has been booming for the past couple of years with strong job growth and population increase.

Its proximity to major highways, including I-10 and I-65, enhances accessibility and facilitates commerce, making it an attractive location for businesses seeking logistics and distribution centers.**2.

And if so, what is the cost and prospect for collecting something, certainly not all, but something.My thinking is that if it shows up on their credit, it may hamper employment, car purchases, rental applications, education funding, etc and at some point they would need to pay me to go forward with some major life steps over the next 10 years.Your time and money would be better spent updating your rent requirements to get better tenants, increasing deposits if allowed and proactively evicting tenants who are behind so you don't get back in a position where someone owes you a substantial amount of back rent. 

Do you need help attracting renters?

Between 2004 and 2007, interest rates increased from 1% to about 5%.

I checked out your listing and read what you're doing to attract PTs (prospective tenants) and pre-screen them, and here are my takeaways:-No offense intended, but your marketing photos could be better. 

Any investors in the Houston area with experience in building an addition for a home to increase square footage and add value?