I have been a therapist for many years, ( ~ 38-man I sound old) and have studied many theories and learned many therapeutic techniques, some more valuable than others. However, what's most important is the therapeutic relationship between client and therapist. A client must come to trust their therapist, feel accepted and have faith that their therapist knows what they are doing clinically. That being said, I have found Cognitive Behavioral techniques,, EMDR for trauma, Acceptance and Commitment therapy and others effective.