I've taken note of and talked to the owners of cars I see at shows and cruises that have exceptional looking paint, and while praising the paint I ask how old it is. If the paint job is more than a few years old, ask the owner their opionion of the shop that did it, and get the name if the response was positive.

In any given area, you'll get a couple of names that keep coming up. That's a good place to start. The lacquer on my car was done in 1983 at a cost then of over $6000, but the painter has since retired.