If the bumper is a new one, then it comes already primed. If you are not satisfied with the priming, simply wet sand the rough areas. You can proceed to clean it with any paint prep product. The next step after this is to carefully and evenly apply the base coat from a distance of at least 9-12 inches away from the bumper surface. If you find any imperfections, you can apply the base coat at least two more times. Finally, apply the clear coat shine laying, using the same techniques used for the base coat.