if you have actual cracks and chips, wet sanding won't get rid of them.....buffing will help make the cracks less noticeable, because it heats the paint and causes it to expand.....if you're not looking to get a new paint job, I'd recommend just buffing/polishing out the paint as best you can....if you have a clear coat, and the chips go through it, there's nothing you can do really, because the basecoat underneath cannot be polished to a high gloss....good luck with it either way