Yeah clean and clean and clean. Wet sand the rims first, some say you need a primer but when I did it I didn't use one. Light coats that are layers look better then 1 heavy coat.
i used airplane paint stripper, it removes the clear coat on the rims, then i used a primer and a few coats of w/e paint ur gona use, if u dont remove the clear, it will flake off easy because it cant hold onto the rims material.
Aircraft stripper is pretty mild. Remember its application is removing paint from airplane skins, which are ~5 thou thick aluminum. Anything aggressive will weaken the skin or bore right through it. Use playing cards around the rim to keep it off the tire, if you're concerned.