Auto body repair & detailing: repair scrape/dent, grit paper, old paint

Question
after cleaning the panel that has a small dent/scrape, what do you sand the dent[apx 1/8 deep] with before you apply the filler ?
do you sand off all the paint and primer around the dent before applying the filler? I am capable of flat sanding and shooting primer, and base coat clear coat. just need help with the above. thanks for your time.  bob

Answer
The easy way- sand the area with 180 grit paper, and apply a coat of USC Icing body filler pn 26006. Block sand the icing with 150 grit paper. Skim coat with another coat of icing, final sand it, and the surrounding area, with 320 grit then prime. The hard way- using regular old filler to save a few bucks- grind dent with 36 grit disc, feather area back with 80 grit on a DA sander. Apply filler, then block sand with 80 grit. Feather back around repair with with 180 on a DA sander. Apply a skim coat of filler. Sand this lightly with 80 grit, then follow with 150 grit. DA around repaired area with 320, then prime. Most regular body fillers CANNOT be applied over paint, but Icing can be. It will adhere well, without attacking the old paint. The end result will be a much smaller repair area. Hope this helps. Bill