There are so many niches you can focus on: Student rentals by SMU, C/D class homes in DeSoto, high end rentals in Preston Hollow(ok maybe not there, but you get the point), SFRs in Grapevine...

You may have to kiss some frogs before you find someone you are happy with.

Doorstops...the springy ones get damaged easy and you constantly replace them; friction stops are very hard on hollow core doors.

You did not mention the scars that you get along the way, but we each have a few.The one thing that I learned early on is to "Eat your Frog" first thing.

There are hollow core doors throughout the property, and I don't believe there was a single one without a hole in it of some sort, plus damage to drywall, carpet stains, missing vent covers, the list goes on.  

A frog in water does it feel it begin to boil until it's too late.

That RESPA rule is terribly hollow and always has been. 

Kind of like the frog in boiling water.

I wouldn't put carpet back in it; laminate wood grain will cost ~ $0.77 SF and 12' wide tile pattern vinyl sheet ~ $0.49 SF plus installation. 30x80 interior door slabs: smooth hollow primed $44; six panel hollow primed $54; either will require cutting/installing the lockset and mortising for hinges (handyman work).

With long rifle hollow points and emptying a clip in about 4 seconds not many people would keep going through the door!