My approach is similar to lolagrace. I never "interviewed" my T. I found T on PsychologyToday and b/t that site and T's personal site, I had all the info. I needed. I knew his educational background/training, how long he has been practicing, what he specializes in, and his policies (T has all his written policies posted on his site regarding contacting him during criss, cancellation, session fees, confidentiality rules etc.).

When I first met him, our conversation started off with me describing why I was there and it flowed naturally. T stated an observation during our first session which led to believe that he was paying attention and understanding what I was trying to tell him indirectly. By the end of that 50 minutes, I felt comfortable with him and felt that we would be a good match. He didn't get me 100% but based on his questions/comments and general attitude, I felt that with time, he would get me.