I know I'm late to this party, but a tiny piece of adhesive backed sandpaper around 320 grit, stuck to the end of a pencil's eraser ... works perfect as prep. If the car is black like mine and you have some spray paint, tearing a small hole in a sheet of paper then holding it above the surface (masking, sort of) works well. The paper blocks overspray from the surrounding area and gives the touch-up spot a soft edge that blends in a lot better than brush touch ups.