"sandpaper" and "polish" just don't belong in the same paragraph !!!

You want to polish you use buffing wheels - start with coarse compounds and work to finer.

I've found that the automotive compounds work well and are less work than using the hard blocks. A little water will allow you to buff longer before re-applying compound. Use the red compound to start and the white "clearcoat" compounds next. Finish up with something like the "powerball" and Wenol. a final coat of wax will help minimize oxidation.

BTW - you'll want to use something like a diegrinder to spin the buffing wheels - a drill just doesn't have the speed. You can do the final "powerball" with a drill.