I wanted to paint the walls.

It's just a basic rehab, new roof, new kitchen, new bathroom, paint, new flooring, new fixtures and the yard.

He/She will handle all the paperwork, lead paint requirements, etc, and the cost is usually just 1 month's rent.Otherwise, check out https://www.ezlandlordforms.com. 

I bought this duplex 5/17 and put in new appliances, floor and paint. 

Tenant A moves in, trashes the place, lets their animals crap/piss everywhere, paints the walls black, lets the lawn die, doesn't pay rent and utilities for four months, and then disappears.

Be sure to paint the wall behind before you install the toilet.

It's easier for them to just ram through a new city ordinance and paint the state legislature as the bad guys when it gets overturned. 

At that age, some probably need roofs, HVAC, water heaters, etc. and all need carpet, paint, appliances, the list goes on and on.

And of course, in older homes, if you're sanding, etc. be mindful that old paint often contains lead. 

I would calculate for paint, flooring, and new kitchens for all units if you plan on doing that and add big ticket items on top of that.