I think I know what you're talking about, every time my boa strikes at its prey I jump a little. I kind of feel like I might get struck sometimes too. I use hemostats and hold the rat by the tail, luring the snake to get a head strike. I try to keep the rat moving more than my hand as well. It's not too difficult to get used to, a few feedings will give you some confidence, just make sure you have respect for the snake.

It might help if it is warmed up more too, they can see thermal differences and would be less likely to be looking at your hand as prey. You can also use hemostats or longer feeding tongs.