One method I use is to put my sandpaper on a sanding block. Then I put tape on the sandpaper leaving a small center section exposed to the sandpaper. The tape holds the sandpaper off the paint the thickness of the tape. Applying pressure can get the run down to the level of the top coat. Different tapes and plastic films vary the distance the sandpaper is held off the finish. For small problems I can avoid putting other products on a new paint surface.