Auto body repair & detailing: Rust spots, rust spots, auto sleeper

Question
After removal to bare metal what procedures do I follow including best materials to use. My vehicle is an Auto-Sleeper VW campervan based on a Kombi minibus, W reg(2000). The rust spots are appearing on wheelarch flanges and on the lower side skirtings. Thanks

Answer
Use a high grade body filler  to smooth it over and then use a self etching primer to help seal any bare metal let dry then apply 2 to 3 coat urethane high build primer. sand area with 400 grit paper your now ready for paint use a good urethane weather it is clear-coat or single stage