Right or wrong, this is what I do. I prep the metal by either sand blasting, grinding or high speed wire wheeling the surface as clean as I can get it. Blow off the residue and wipe it down with paint thinner and blow it dry. I got some stuff at my local body supply store called SEM rust-seal. I paint that on and let it set over night. The next day I either brush or roll rustoleum gloss enamal over the rust seal. After I assemble several parts, I paint another coat over everything that may have been scratched or scuffed in the assembly process. Here in the rust-belt, you have to take as many precautions as possible to stop/prevent rust.
Scott
