I ask questions at my eye exams when I don't understand why something's being done or what a given test measures. Ask them to explain what they're doing as they go, and ask them to tell you more about what your prescription means. Their answers should either make you feel more confident about the quality of the exam they're doing, or not, in which case you should ask around for local referrals.
You can get recommendations from your doctor (or pediatrician). Your doctor will have the names of eye doctors in the area. He or she may have a sense of who would be a good fit for you or your young children or recommendations from family, friends, and coworkers. Think of everyone you know who wears glasses-they all have eye doctors. Ask them. Professional organizations. The web sites of the American Academy of Ophthalmology and the American Optometric Association both offer ways to find local eye doctors.