If I go to Home Depot and spend $500 on a new bathtub, a door, paper-towels, a new screwdriver set, windex, and valve stems for a faucet; would I break these down into supplies, cleaning and maintenance, and repair with separate entries?

Do we invest in a 3-4 unit older home with good rental history but probably needs quite a bit of maintenance (and might not attract the best quality tenants at the rental price point) or do we go with a newer duplex that is basically turn-key but doesn't have a rental history because both sides were owner-occupied?

@Cole Fisher Assuming you're planning to self-manage, I'd include vacancy and maintenance/repair estimates.  

Maintenance will be a nightmare.  

I would make the tenant buyer responcible for everything from cutting the grass to general maintenence. 

The cost of management -- again, unless you're comfortable there -- trying to track down late rent, finding good renters (since most good tenants want to live in better areas), along with the higher maintenance costs associated with bad areas all tend to wreck any profits the theoretical numbers show.

Do you do regular maintenance inspections?

Yard maintenance, dealing with the City inspectors, etc.

I manage and do most all my own maintenance with the exception of most of the major stuff.

Their solution is to call an 800 number (not a solution since their number wasn't working), go online (not a solution since their online site is down for maintenance), or go to a local office.