Sanding with 400 wet-sand is fine. Would recommend an adhesion promoter be applied before color though, then spray color to match (let coats dry to "finger touch" between coats) then apply clear. No sanding between color and clear, maybe "tack- cloth" off but only if not metallic since you could otherwise "drag" the metallics and that would definitely show. Let clear dry to touch between coats,(usually 2-3 coats). If you have access to a heated booth that would be great but if spraying "outside" plan accordingly with temp and longer dry times. Patience is the key thing here! Good luck!