I'm not sure I'll be able to help...
My number one rule for overcoming fear would be... Let it slide. From what I've read, it's not like that for everyone, but by being docile, normal, and only gradually changing... Until you're confident enough to "jump", of course... Trouble just doesn't tend to stick to you.
This is true for many domains, not just transition. If you "slide", trouble eventually "slides" off of you. If you cover yourself with spikes, trouble will stay. For example, when I was in primary school (probably ~8 years old), I used to be bullied a lot, because I was shy, distracted, wore glasses, dressed in blue a lot (yeah, children don't need a valid reason to bully), and was somewhat fat. I soon learned to naively smile back at insults and ignore bullies.
At first, they were really frustrated by my unexpected reactions and worsened the bullying. At one point, one boy even tried to behead me (with half of a "for sale" sign; nothing serious, but he really WAS angry), and when I just let him do it for a while, and even moved my muffler away to help, and pretended that I was okay with it, he just rubbed a few times, barely making me bleed, and went away. After that event, things calmed down quickly. I was never really bullied again after that, until secondary school, where the initial pattern of "bully, bully more, then stop bullying" repeated itself, although on a much shorter period (3 years 1 year). The bullying then stopped forever.
To come back to transition, the "let it slide" method seems to work well for me.
First I started only buying women's jeans on the excuse of my round butt, then shoes on the excuse of my wide but short feet, then I bought a theoretically andro but quite feminine anime bag as a purse, then...
I think that the best way to fight fear in general is to allow yourself to be a scaredy-cat and use excuses, and go gradually. Don't force yourself to jump until you're ready. The pressure of "I must go full-time" or "I must pass" is just going to add to the stress. Take it to your own rhythm.
Don't hesitate to use tricks and excuses, especially in the beginning. Scared to come out? Send an e-mail. Scared of what the clerk thinks of you when you shop for female clothes as a male? Pretend that you're looking for a birthday gift for your twin sister who almost has the same measurements as you. Scared of showing your rather feminine hat? Say that your sister knitted it for you.
For example, when I was really incapable of passing (I can now pass with a high success rate under certain conditions (like, using a scarf), I said that my feet were so wide but short that I had to buy women's socks. And the clerk, just like that, proceeded to telling me how there's no shame; how her husband, too, wore women's socks. All stress avoided!
I'm sort of in an objectively weird in-between stage, still presenting as male, but wearing misleading androgynous-but-more-girly things, and long-ish hair, with a somewhat feminine voice. At first, the vast majority of people were very cold to me, weirded out ("oh no; I'll catch the gay!" or almost), but didn't display any animosity, since I didn't actually provoke anyone.
And this term ("semester" of 4 months in college), helped by hormones, I started talking to others a little more, and helping them out, uncalled for, when they asked their friends for advice and they couldn't help, in programming classes, where I'm more comfortable than most (having ever done some "fake" game-specific language programming, and discovering by coincidence that it was similar to Javascript in many aspects).
After their initial reaction of unease (even apparent on their mouths), seeing that I'm a helpful and nice person, they are beginning to accept me more, and they now even ask me for help, thank me, and even sometimes talk to me without a need for help. And they're visibly more at ease with me. there's still some unease, at different levels, with some people, but the vast majority are accepting me.
I was a weirdo "gay" (even tough I display no homosexual, or stereotypically gay, behaviours that I know of); and now I'm turning into that strange, but nice and hard-working, person.
All of this, I think, is slowly preparing them for when I come out & go full-time, anywhere between next Autumn and the following one.
I hope I was helpful.
