Look for good printing, not good design. The creative part of printing most often rests in the client's hands so a printer is more concerned with science than art. Check for bright and clean colors, for smooth, dense solid areas and text and images that are focused and clear. Though it is by no means a rule, it is my experience that price is a fairly good gauge of quality. You don't need to be Gutenberg to figure out why.
Busy presses are the name of the game.
Ask the right questions Finally, once you have narrowed the field to two or three candidates that can produce the quality you need, it is time to get price and time estimates. Tell the printer which two you are most interested in and then insist on a reasonable mix of all three. For simple one color jobs, one price may be adequate. But beyond that, it is good to get at least two and often three estimates on jobs over a few hundred dollars. Even if I have worked with a printer over a long period of time, I bid jobs out to others from time to time to keep myself in touch with current pricing.