A good massage therapist is someone who listens to you, is attentive to your needs/wants, and uses their knowledge base to customize your experience. You should feel comfortable asking questions throughout the session so that they know how much pressure to use (or not use). They should be able to find the spots that are causing you pain, and make sure they work on those areas. They should also be able to tell you how long it will take for your muscles to feel better, and what else you can do to help speed up the healing process. A great massage therapist is passionate about what they do and how it can help others. They enjoy working with people and want to help them feel better.
The best massage therapists are the ones who listen to their clients, who know how to get your body where it needs to be, and who respect your comfort level. The best way to find out if a massage therapist is right for you is to book a session with them and see how they work.