Pre tapering and taping off the area are good ideas. Also, a round tool creates a flat surface. I use a 1/2 round file for rough work, then sandpaper. Avoid going across the grain once you get close. Take your time, good light, magnification if your eyes are as old/poor as mine. You can take a little glass, but try to avoid getting onto the glass until you are down to 220 paper. I generally go down to 320, 400 before the first coat, then 400 (wet) between coats of finish.