I would mostly tell a litte of my story and see how the person "feels" to me, how they respond. Other than that I'd just see if they had the degree/training I preferred? But a lot of "technical" things could be checked out before seeing them so I could concentrate on how they responded and whether I was comfortable talking to them. I got my best T from another T I had for group who interviewed me and then suggested I call my T and see her. The other, group T knew me/my situation and was a wise old T :-) so it all worked out well.