Talk to owners of tinted cars where they've taken their cars. And ask if they recommend the shop to you. You maybe surprised by some of the answers.
As for the shop itself, every one I visited said the same thing....they're the best in town, their prices are the best, they have the best film, they're the best in their trade, etc etc. Use your judgement to select the shop. I look for clean (relative) shop, comfortable workplace (air conditioned, etc etc...it affects the workmanship you receive), single owner/operator business, warranty of product and labor (not all shops warranty labor), and selection of films.