PRIMER! Definately. Hit it with primer, then wetsand it with like 600-800 (I think that's the grit) grit wetsandpaper. Primer it again, then wetsand it again until it's baby-butt smooth(SEEKER's words!). The smoother the primer finish, the better results you will have, in my experience. I RNB-ed my gauntlets and helmet and Fett Girl did the same with her armor and helmet.
Wes