Different strokes for different folks.
We strip to bare metal and carefully clean the metal.
Apply epoxy primer to seal the metal from moisture.
Do metal work and then spot reprime, if necessary.
Do filler work (many fillers can absorb moisture).
Apply a surfacer, and follow instructions from the finish-paint manufacturer.
Stick with one manufacturers products, and use them as recommended by the manufacturer.
Many people have posted good experiences with Southern Polyurethanes.
