Start slow and build up to a speed thats effectvie and that you're comfortable with, you'll be moving across the panels a similar way to when spraying so you set it up to suit you.
Try a finishing head and G10 compound first. That will get rid of swirls and light marks in laquer/topcoat and won't do too much damage if your technique aint all that, but if you're trying to make a pink car into a red one, you might need to flat it with 2000 grit first, or just get stuck in with a cutting head and cutting compound then use the polishing one after to bring the shine up.
Keep a jet wash handy, keep everything wet and get rid of all the residue before it dries cos it's a bastard to get it out of doorshuts and behind mirror glass and stuff.