After I stripped the layers of paint off, I sanded with 120 grit sandpaper.
The floor on the landing was badly damaged as well and also had layers of paint on it. So I picked out a laminate flooring and decided to stain the stair treads the same color. The laminate I chose is Mannington Historic Oak in the color charcoal
Since the laminate is weathered, I selected 2 stains that closely matched and mixed other colors to match. There are a couple coats of stain with a little light sanding in between coats. I also watered down some white paint and washed it in to some of the open grain.