Best as in for keeping clean? That's going to be a ceramic coating realistically. If you want them looking perfect, then you're looking at taking them off, refurbing and then doing the coating. However, if its not going to be a showcar and you just want looking good and keeping clean easily, then just removing and giving a thorough clean and decontamination and then coating. By decontamination, that involves:
Pre-washing,
Iron fallout remover,
Contact wash with shampoo,
Tar remover,
Claying.
If it was bodywork, then you'd want to machine-polish to get the clearcoat looking its best (removing the marring from, amongst other things, the claying process) but probably not completely necessary for wheel barrels given the lack of exposure.
Otherwise/Also, I'd look at low-dust pads when you change (I've got ATE Ceramic pads on order as good reviews) and decent barrel brushes to clean inside when you do do it.
Personally, I'm happy just keeping my clean with brushes when I clean the car.