Electrical work, plumbing, foundation, windows, roofing, and AC/Heat.

A nice portfolio is 10-40 properties, and yes you should drive by your own assets to check for broken windows.

WHEN (yes I mean WHEN not if because over 30+yrs it happens many times) when the market has a drop for whatever reason be it a bad election, war tensions, someone sneezed on there terminal and HFT's went bazerk selling, whatever the cause, WHEN the market drops you get a "Margin CALL" and next thing ya know there not just selling off those leveraged positions BUT there selling em off in the drop, at the lowest price, amplifying losses, all those returns going out the window in moments.     

A window and a door qualify.4 - Minimum ceiling height of 7ft.

I make sure they're well insulated, have replacement windows, spend more on nice flooring that looks great (plank style / wood-look porcelain tile, hardwood or click-together LVT planks, not peel-and-stick squares). 

Added a bathroom and remodeled existing.Opened kitchen to diningNew roof, driveway, windows and mechanicalsRefreshed landscaping, hardwood floors and paintWhat was the outcome?

What was nominally a 52k down payment turned into close to 100k--12k in closing costs, 12k in extra payments, and about 25k in labor to help me get it ready when I realized I couldn't get it all done by myself working evenings in a reasonable amount of time (plus I knew I couldn't do the egress windows myself). 

Class B- midway between Class A and C, school are decent but may or may not be highly ratedClass C - lower purchase prices, schools aren't usually highly rated, higher crime, lower income tenants and homeowners, mix of well maintained and badly maintained yards, streets have run down cars, some homes with boarded up windows, mix of renovated and older homes.

They charge and collect the late fees you might let slide.

Get a good exhaust fanEven if your bathroom has a window, I would still suggest this.