Refinishing stainless steel trim

The starting grit depends on what you're taking out. If you're fixing dents you might start with 220. It's like body work but without the filler. You have to get the piece as flat as possible using a small hammer and punch. I like to use a 1/4 inch drive socket extension as the punch because it has rounded corners. That or a small piece of hard wood. When you think you've got it close, sand it lightly with sand paper on a rigid block, like a small piece of wood. This will identify the high and low spots. You will usually have to go back to the hammer and move the metal a few times until the high and low spots are mostly gone. Then you sand until you have eliminated the low spots and then start moving up through the grits as chrisf described. The better job you do with the hammer and punch, the less material you will have to remove with the sand paper, so try to get it as flat as possible before sanding.

I've had good luck using the DA, but it's risky. Especially if you have the cheap DA like mine with the counter weight behind the pad. I've slipped off the piece and made some nasty marks that had to be sanded out.

Caswell Plating is a great source for buffing wheels and compound.