A good paint job is 95% preperation. If your old paint is chipping off then the top coats are not adhering to the material under it. Get rid of the cause and either strip with removers or DA (dual action) sand down to prime coats. Block sand and featheredge as required with grits ending up with 320 to 400. Then epoxy urethane prime, color coat and clear coat. Finish by wet sanding with 1500, then 2000 grit, rubbing compound, etc to obtain desired gloss.
