the places with minor rust, i woul,d sand the area with about 80 grit, where the rust is to bare metal, bondo it up (if the rust is only on the surface) sand the bondo with 120 then smoothen it out, move onto 240 for the entire area being painted, then once again with 320, prime the bondo, then sand it with 400 grit. and then of course with the big missing chunks on the bed, you will have to grind out that area, cut out a chunk of the rust, and weld on new metal. hope that helps!