O'Neil patches shallow holes and divots with Ready Patch because it dries fast, sands smooth, and stays flexible. Deep cracks and rotten spots are best repaired with two-step epoxies, such as those made by Advanced Repair Technology. (For a step-by-step instructions, see Repairing Rot with Epoxy.) The days of using polyester auto-body fillers on wood are over. "They cure too hard," says Portland, Oregon–based painting contractor Kathleen George. "They look good at first, but then they peel away." House Painting Westminster
Rotten wood and siding material are nearly worthless to paint, as they will do nothing but to continue to deteriorate. You have a couple of options. Replace the siding or wood trim with new components, or in the case of small areas, use a wood hardener and match with an exterior filler product, such as a wood filler. Be sure to prep and sand either one prior to painting.
The rule of thumb has always been to apply a good coat of primer, sand, then apply your color coats. This is still a good rule to follow, but new paint technologies have combined primer and paint into one product, which manufacturers assert will cut down on the number of coats you will have to apply. This newer paint is more expensive, but may be comparable to the purchase of separate primer and paint. Look at reviews of these newer paints, particular from folks that have used it in your area. House Painting Westminster