i started out feeling like i knew nothing (and i still feel like the OP) and i let the other nurses know it. that method worked like a charm for me during my clinical experiences and internship so i stuck with it when i got hired. i would get with a nurse when i was training, ask if she was comfortable letting me do things or prefer that i observe, and then do everything i could get my hands on. my peers would be like, "i just got to watch." that's because they stood there and watched and asked too many questions (testing the vets).
my first day giving meds with my preceptor i was like, "i'm sorry if i'm slowing you down. it would help if i even knew what color the pills were, but i don't have a clue." that doesn't mean i made myself look like a fool either. i could tell them what a medication was for, what the therapeutic dose was, the side effects to watch for....all the textbook stuff. BUT i had never seen the actual medicine or ever actually touched a peg tube. i made it clear that i didn't have a clue, but that i knew who DID and i wanted THEM to teach me. other nurses (not just my preceptor) would come get me to start IVs, blood draws, etc. they acted like proud mamas instead of the "nurses who eat their young" you hear about.
of course, on the job it's a little different because you're expected to be able to function on your own without a LOT of help. that's the way it should be, but it can be scary when you run into a situation you haven't dealt with before. when that happens, i still go with the old, "this is what i'm thinking, but i've never done it....will you do this WITH me" (not for me) approach. so far, it's worked like a charm and kept me from having a MI. it really is true that practice makes perfect. i laugh now thinking about things i used to be terrified to do. nothing but time and experience can make you confident. i'm still not fully confident either...just aware enough to know what it will take to get there.