The process of wet-sanding a freshly painted car is where most amateur paint jobs go wrong. Wet-sanding levels the paint surface and removes orange peel, but it also removes clearcoat. Do it wrong and you sand through to color or primer.

The sequence: let the paint cure fully — at minimum 30 days for a urethane, longer for lacquer. Start with 1000-grit, wet, with a soft backing block. Sand until the orange peel is level but stop before you see color showing through. Progress to 1500, then 2000. Finish with machine polishing compound on a DA polisher.

Guide coat helps here too: spray a thin coat of contrasting color before you start sanding. It shows you where the high and low spots are. When the guide coat is fully removed, the surface is level.