what problem are you trying to solve?
Have any pics of what you're working on?
Claybar will do a "light" removal of oxidation/scatches.
Products like No. 7 white polishing compound remove somewhat more oxidation.
Rubbing Compound ususally is a much heavier grit and can scratch your paint.
As far as using a buffer, it can be dangerous if you haven't used one before. A variable speed polisher is a lot safer.
Again, it depends on what problem you're trying to solve.
2004 E60 530is, Delivered 12/12/03, TiSilver/LGrey, PP, SP,PS, PDC, ACC, FRS, Step, Xenons, clear bra, body colored rear inserts. (Retired, 1983 henna red 320is)
2004 Corvette Z06 Commemorative Edition