What color and how to paint old hardwood floors?

[Angela Smith]

We are prepping a SFH for a long term hold rental. It's a 1940s bungalow in a blue collar neighborhood. Walls are painted a very light gray. Trim is bright white. The floors are currently painted dark brown. They are peeling badly. They were not prepped and painted properly by the previous owner and they look awful. We have begun stripping the current paint which is a very easy process, thank goodness. But, we want to repaint correctly. We need advice on prepping the bare surface so the paint will adhere and not just peel away like we are seeing with the current finish. Also, what color will work with the light gray walls and white trim?