Auto body repair & detailing: prpare for painting, grit paper, prime areas

Question
proper technique for sanding and surface conditioning prior to painting, no rust involved just sanding and primeing.

Answer
Feather edges with 80 grit paper untill you cannot feel edge. sand surrounding areas to be primed with320 grit paper. Prime areas with a good self etching primer working frome first coat on the outermost covering all.  Second coat moving in a couple of inches so you dont prime over the overspray..Three coats should do.  let dry 24 hours. resand with 320 wet or dry sandpaper untill smooth. wash take off any dust and you are ready to seal and paint