It is SOOOOOOOOOO hard!!!!!!! SERIOUSLY! One option FYI is to see if there's a university in your area with a clinical psychology program. Oftentimes, universities will be really good at giving referrals to qualified providers. That's what I did last year when I was looking for a T. They gave me a list of names and then they said my T's name and said, "Oh and this one might be kind of far for you to drive, but she's really good." So I called her and made an appointment and immediately LOVED her. Now, this T ended up having to move away last month

but I'm really glad I got to work with her over the past year.
My current T, I found through my insurance. I looked her up online and she had a website. Through her website, I found out that she specializes in my exact problems. So I emailed her. I knew she was the T for me when she took time to speak to me on the phone at length about my problems before I was even her client. AND, before I was even her client, she asked to speak to my old T to get a sense of things from her as well. This is all before she saw even a little bit of money from me. So this all told me that she cares about her job.
I agree with WePow's advice. Interview them on the phone. See if they have experience in your specific problem. Think of some things you would want in a T. Like, what did you like about that one T who ended up working at a different facility? Then see if you can come up with a few questions that will tell you if the T you talk to is right for you. If they're not willing to answer a couple questions on the phone, I personally do not want them as a T, but that's just me.