Finding therapists and providers is somewhat of a personal choice...for those running through insurance, the choice becomes limited by what the plan pays for. If you are participating in any local TS support groups, feel free to ask for recommendations as well as names of shrinks to avoid. But do not think you have to limit yourself to the 'gender therapists.'
I figured out early on that the gender mills were NOT the source for me to find competent care. I ultimately had as my primary therapist a referral from a friend who had previously been in counseling with a lesbian loosely affiliated with a gay and lesbian healthcare initiative. She accepted the insurance plan I had at the time and the insurance company had no issues with the billing so all was good. More importantly was that she grasped the reality that a transsexual could also be a lesbian post-operatively...there were too many dinosaurs in the gender mills as recently as 25 years ago that would not work with a client who did not express a desire to leap off the operating table and be Suzy Heterosexual. That at least still has changed somewhat from what I gather, but I still would tend not to refer someone to a gender mill...
My endo was also sourced through the gay and lesbian community. I shotgunned a few letters out, having been burned by one provider in the mid-80's. No letter from the shrink was required, he provided pharmaceutical samples on many occasions and he was willing to bill the insurance with non-gender-treatment coding which meant all I had to cover was the $15 co-pay every few months for the blood work. Later on, I shifted a lot of my care to an OB/GYN closer to the house since, after all, I figured I ought to establish THAT relationship in case I needed some attention in that part of my body. The fact that she was a lesbian helped matters significantly...