One thing that always helped me with that sort of stuff was walking down every procedure over and over until I got it down. But then, there is no replacement for experience. If after you've walked them down and asked questions, you still don't feel ready..., TELL SOMEONE. That isn't to say you should try to get relieved, but like Drayer said, get someone to help you, or monitor you. There is nothing wrong with asking for help when you need it. In fact, that is a sign of a good operator.
Good luck and keep us posted!
Justin