We just did basic paint, carpet, cheap laminate on sale from Floor n Decor, swapped  bathroom fixtures and ceiling fans for a new ones (also on the cheap), fixed a fence, painted a back porch --- done! 

One I met recently converted a garage into a bonus room yet didn't put in a closet and skimped on paint on the whole house.

Paint is cheap.

This is a "painting with broad strokes" kind of discussion as other have pointed out. 

I have also had new spouting systems and flashing added.Apt 1 has been completely remodeled, with upgraded appliances, renovated kitchen, new flooring, paint, and two complete bathroom remodels.Apt 2 has upgraded, kitchen, flooring, paint.

I finally just used KILZ oil based paint and painted everything with at least 2 coats. 

I know some Landlords will offer to give little bonuses like painting an accent wall with whatever color the Tenant chooses or something like that.

Overall the tenants pay more for rent and those paying less than market rent end up with minimal maintenance performed on their units For example why paint or replace the carpet if tenant is below market rent because if tenant gives notice the unit will be brought up to current market rent!

Something along those lines, just paint the negative as a positive. 

Use it to provide consulting services, speak on your area of expertise, conduct e-commerce, sell finger paintings, or whatever you want.Create affiliate content - It's hard to get scale here, so you either need a targeted audience that will buy larger dollar items or a big audience on some platform.