Remove any drawers or shelves on the desk that have contact with the desk top. Pulling drawers out completely is much quicker than taping off the edges to prevent excess stain or paint from dripping.
Remove the existing finish from the wood. If the desk top has peeling paint or a varnish that has mostly worn away already, the quickest way to do this is to simply sand off the finish. If you have a thick finish to remove, use a paint stripper designed for use on wood.
Sand the desk top down to remove nicks and scratches. If you used a sander in the previous step, it will simultaneously complete this part of the refinishing process as well.
Wipe the dust from the desk top with a soft cloth dampened with a wood-friendly cleaning solution.
Paint or stain the surface of the desk. Use a solution that incorporates the primer into the paint so that you do not need to prime the surface in a separate step. Choose a quick-drying paint or stain so you can apply subsequent coats in just a few hours and finish the entire project in less than a day.