Once you knocked out this wall you realized you had to rerun new plumbing and electrical... etc.

Great job on taking that first step but please knock it out and move to the next.

I would build up reserves and then make double and triple payments each month to knock down the principal quickly. 

I decided to knock on the neighbors door to see what was up.I told him that I purchase houses and was strolling around and if he knew about the house next door.

Also, I knocked down and cut up a large tree for them, for free (they paid $450 for haul off) when they were quoted $2800 for removal. 

A skill in real estate dealmaking is recognizing the scope and scale of problems and discerning the gap between principals understanding of the severity and reality.If the knowledge gap is small, and they are super motivated, you can offer structure a deal to take off the market, manage expectation and control the asset while you solve the problems.If they're in la-la-land and think they can do better, best to decide if you'd ever want in the deal then, if yes,be patient while tgey knock themselves out mash it around.Most any real estate problem can be fixed with enough to money.

Basic clean up, still needs rehab when I sold it. after, just cleaned it out, knocked out some walls, cleaned the yard up.

That's really great advice and will allow you to knock out a bunch of important tasks before your hectic work day prevents you from getting those tasks done.

You can knock this out in a couple days". 

Going to attempt to knock them out this weekend for sure.