How would I know if I have the right therapist?

It's kind of like an audition.  You need to find someone who you feel comfortable with and respect.  Many therapists provide short, free, consultations.  That is a good way to see if they seem to understand and empathize with you in a way that puts you at ease.  If you have specific issues that you need to work on. look for someone who specializes in what is troubling you.  The therapist should be able to provide evidence-based treatment and should discuss with you why they think this is the best way to proceed.  Every counseling client should feel free to have input on their goals and desired outcomes.