I talked to my normal therapist (who also treated me for general anxiety and depression) for 12-15 months about my gender issues, but she had no real experience with transsexual patients. Still, she had some contacts who found me another therapist who had much experience, who was aware of my past therapy, and so after 1-2 sessions was totally willing to rubber-stamp me for hormones.
(We were able to find a local endo who was sympathetic, but he didn't have any experience with beginning TS patients, he was only used to working with post-ops who didn't need as high doses. So he referred me to Johns Hopkins, where I am going on Friday, hopefully to get a gameplan for hormones.)
As far as being ready... there are a number of factors. Emotionally I am more than ready (I'm 39 and have been contemplating this a long time), but financially and logistically, I am trying to make sure the other parts in my life are smoothed out (job, family, etc.) before I commit to a tentative schedule, since going on hormones will definitely cause physical changes that will soon enough lead to a RLT. It's hard to balance them all.
If I had to advise someone, while every situation is unique, in general it is good to make sure you have a relational support system in place, and steady income/insurance, and other things you can depend on before going ahead. (But I understand that the emotional severity of things sometimes is enough to override those things.)
~ Jennifer