Where I live there are almost any gender therapists...
All the private therapists aren't used to deal with the trans community. Only a few have the experience. On the public system there are a few more, as we have specialized services for trans people...but the waiting until the first visit is enormous...
I decided to talk with a private therapist before the public and she was very nice with me. I told her basicaly all the problems of my life and about my condition as transgender...but I can't express myself very well and things are not going where I would like them to be because of that...sometimes she thinks I don't have enough life experience to decide that this is the right thing for me...but I feel it deeply inside and I think that my lack of experience is due to the fact I am on the wrong body....
My advice: open up and tell everything as clearly as possible. The therapist will conduct the questions, so it is up to you to tell her everything and to tell the truth all the time. Be sincere and the therapy will be great!