When choosing a shop for a vehicle that is not under warranty, first talk to friends and family to see if they recommend a place to take your car.
Also see if the facility as been certified by the National Institute for Automotive Service Excellence (ASE). The certification means that some or all of the mechanics at the shop have met basic standard of knowledge in specific technical areas. For example, some areas may be brake work, collision repair, engine repair, painting and alignment.
Even better, find out if the shop is in the ASE Blue Seal of Excellence program. The initiative recognizes shops that have 75% of their mechanics ASE certified and have a mechanic certified in each area of service that they offer.
Often shops display the Blue Seal plaque in the customer waiting area. If you don't see it, don't be afraid to ask if the facility is Blue Seal certified. You can also visit the ASE Web site.