Painting any part of your staircase requires careful preparation. To achieve a good finish, you must either find a time when no one will need to use the stairs, or find a way to work around foot traffic. Staircase kickboards, or risers, are the fronts of the steps. Painting them isn't difficult, but if you can't avoid using the stairs until the paint is dry, it's all too easy to ruin the finish with a kick or scuff.
Sanding the risers might require a specially angled sanding tool to remove all of the paint and leave a smooth surface. If you're painting other parts of the staircase, you should complete all of the sanding in one step to avoid more dust when working around wet paint later.
If you're painting your kickboards a different color than the rest of the staircase, you should use lots of blue painter's tape to prevent getting paint where you don't want it. Wrap the bottoms of any nearby spindles to protect them. Tape off the edges of the treads that butt up to the bottom of the risers, as well as the nosing (the bottom of the tread that overhangs) if it is a different color or will show.
When working on stairs, always start at the top and work your way down. Let all components dry for at least 6-7 hours, and then apply another coat. If you need a third coat, wait another 6-7 hours.
Close off your top floor for the duration of the project if at all possible. If your bedrooms are upstairs, try painting stairs so that your last coat will be in the evening. Sleep downstairs for one night, so that by morning the staircase will be navigable.
If You Can't Avoid the Staircase
If you can't close off the top floor, you can still paint your staircase risers without having smears, toe scuffs, or dirt in the paint. You'll just need to tell everyone in your household how to navigate the steps for the next couple of days.
In that case, start at the top and paint the first riser. Then skip a step, leaving the next riser unpainted. Alternate in this manner until you reach the bottom, leaving every other step is unpainted. You will then be able to go up and down the staircase using every other step. Follow the same procedure for a second and possibly a third coat as needed, repainting on the already painted steps.
Once the paint on the first set of steps has dried, you can start painting the unfinished steps. Begin at the top and paint every other step in the same manner.
Keep in mind that children may need assistance taking 2 steps at a time. Pets should also be kept away from the stairs for the duration of the painting process.