Been there myself. First of all, good for you for looking for help rather than trying to "tough it out." Therapy does make a difference.
There are no absolutes, but:
- Look for a therapist with an MD or a PhD from a "non new-agey" school. Google is your friend here.
- Look for a man. As a first approximation, men are better therapists for men (assuming you're a guy) than women are.
- Interview the therapist. A great therapist will not be offended if you ask tough questions - an insecure therapist will be. My therapist was first in his class at an Ivy League med school. I know lots of therapists. Most are more touch-feely than rational, but he is clearly smarter than I am, and that's great.
- Therapists who are qualified to do psychoanalysis (even if that's not what they're doing for you), tend to be the smart ones.
- Stay away from the ones doing EMDR, art therapy, music therapy, somatic therapy, and above all transpersonal therapy.
- Good therapists are unfortunately very expensive.
- A lot of therapists, especially male therapists, are a bit narcissistic. Watch out for that.
- Trust your gut. You don't just need a "competent" therapist - you need someone with whom you have excellent rapport.
All this is from my own experience. Good luck.