I felt the same way at first. Funny, how such a small snake (assuming it's a baby) can be so intimidating. Over time you'll learn that if you are afraid and/or you hesitate when reaching in, the snake will pick up that you are afraid and get more upset when you hesitate. It's like a loop feedback.

Then you just have to accept that you may get bit. It doesn't hurt much, I've been clawed or bitten by cats or even kittens that did more damage and hurt a lot more. The thing with snakes is not so much the teeth but how strong the bite is, they really are incredibly strong. It's like a mini vice grip nailing you for a split second.

Once you accept that you may get bit, be determined that if you do get bit, you let them do it and DON'T yank your hand out, because you can hurt them. At the same time, you do not want them to get the idea of "if I bite, they go away. Therefore, I will bite any time I want to be left alone". Instead, you may have to take a few hits and act like it doesn't bother you (keep picking them up) until they get the idea that biting will NOT make you go away, so what's the point in biting?

Then there's simply the part where there is not yet any mutual trust built up. You don't trust the snake, and it does not trust you. The only way to build this up is some give and take from both handler and snake. Both of you have to enter a zone of discomfort and nervousness repeatedly, and get past it. At some point you won't be getting bitten or even threatened anymore, and also the snake will understand that you aren't trying to kill it.

A good example of zone of discomfort for both is that at some point the snake will be curious about your head and face, spending a few seconds right in front of your nose just checking you out, and then bailing. You're not sure if it's going to nip you and it's not sure if you're going to nip it. Only with a lot of repeating of this without incident is trust built.

This is actually a special time, observe and learn, don't expect to pick up everything perfectly right away -- Like anything else of value, it will take time and effort.