I like to go to local opinion websites, or other consumer review websites such as yelp.com. You may or may not find listings for your area but its worth looking. I found my current mechanic that way and it worked out great. If you can't find anyone there, you can try the AAA website to find AAA certified mechanics. Its not an absolute guarantee of the best or cheapest service, but at least it has some backing as opposed to just picking someone out of the yellow pages. Ask around, ask friends if they know anyone who has had a car worked on and try to get references that way.