I groom Hannah mostly myself but occasionally still have her groomed at a local groomer who is awesome. I was lucky to find her after my longtime groomer moved out of state to start a mobile grooming service. After searching around I finally resorted to stopping a woman on the street who had a wonderfully groomed cocker whom I had seen several time while they were out on their walks near my mom's home, and asking who she went to. I went and visited that shop and asked a ton of questions. Then after seeing a wonderfully groomed cocker at my vets (who sported a full show coat) and finding out that she was groomed at the same shop I had recently visited I booked an appt for my hardest groom dog, Zoe'. They asked me lots of questions about Zoe's condition, did a wonderful job, treated my special needs girl like gold. I was sold. The girls only went there a couple about three years before Zoe' and Maggie passed away last summer, when told that we only had Hannah to bring in they met me at the door with hugs and tears.
Try visiting a couple of differant groomers, look up reviews on yelp (keeping in mind even the best groomer will have people who are unhappy). Ask to see if they have pictures, watch to see how they handle the dogs in their care. Do you have to drop they off all day or do they take them in and start right away. Is the shop clean? Does it smell clean? Google and see if there is a local dog group, maybe shoot them an email asking if they have any recommendations.
Good luck.