Write letters to people whose websites or newsgroup posts impress you. Preparation is the key. Therapy is where you should start. It will help you determine how important this is to you. It will also help you sort out your emotions.
Most people have fantasies or misconceptions about transition.
Therapy can help you prepare for the realities of transition, and how to handle both the pleasant and unpleasant parts. The key to all of this is feeling good about yourself. You are going to take a lot of blows to your self-esteem as you transition. You must have a way to deal with these. Starting a therapists relationship early will also make it easier to get an SRS letter when you are ready.