As a starting point, a client should ascertain that the psychologist, therapist or counselor he or she is considering is licensed by the state where he/she practices. Ideally, a patient would have evidence that the therapist is effective — has this therapist helped patients in the past? Because this evidence may be difficult to find easily, consumers often rely on word of mouth — the testimonial of friends who have benefited from treatment from a particular clinician.
After therapy begins, the best cue is the patient’s experience: Does this therapist understand me? Does the treatment plan make sense to me? Do I believe this therapist will help me? And most important — am I making progress? Patients typically experience a positive response to psychotherapy quite rapidly. If a patient is not making noticeable progress in several sessions, the patient should discuss this with the therapist (and similarly, the therapist should initiate this conversation with the patient if adequate progress is not being attained). Together, a patient and therapist determine when treatment should end and often, this happens relatively quickly. Of course, some problems require longer treatment.
(Source: American Psychological Association)