I am a certified Pet Stylist, Pet Care Hygienist, and a Pet Care Dermatech Specialist. I planned on returning to school to be certified as a Master Groomer, but my trainer Lynne Carver (former GroomTeam USA member and on the Board of Directors for several years)passed away in 2003 and the school was closed.
Lynne Carver, We will miss you!
Anyway... Call around and ask the groomer if they have been trained and certified at an accredited grooming school. Also, ask if they have a portfolio that you may look at. There are a lot of groomers with poor training, or they just don't have the talent even with training.
Also, communication is key to the groomer understanding what you want. For example, I have been asked to "trim the feet" on a toy poodle, when the man really wanted them shaved ("clean feet"). Also, different groomers use different terms, depending on their training, to define a certain type of cut. A lot of groomers don't ask enough questions to clarify and this is what causes a lot of problems.
Hope this helps.