Usually a pro is the only one who can (or should) do the color sanding/buffing with a power tool. Do it carefully by hand and avoid sanding much near edges,
Do a Google search on [i]automotive color sanding[/i] and you will find good techniques and advice.
I did this by hand with a pro-friend on my first paint just (54 Suburban) and had no problems. It took three of us an 8-hour day to get it done.
