A picture of what you are starting with would be helpful so we can give you good solutions.
Wallpaper or contact paper on the face of the risers is always pretty.
If you need to repair damage to the paint, sand down to bare wood, prime if needed, paint, then seal with 3 coats of a quality polyurethane, for protection.
If you're very creative, add a stencil or other artwork to the risers, before sealing, or paint a border edging going vertically up the staircase.
This is a picture of my staircase..help...sos