What to expect/prepare for a job: at a bank as a teller...?

I start training on Wednesday. I just got out of high school and it will be my summer job and then part time in college. I really haven't researched too much about what is expected of me. I have everything in to start, and I have a good amount of outfits I can wear to work already. I am generally a fast learner, but I am still nervous. It is my first job, and I just want to be as prepared as possible. It is actually a credit union I will be working for, I dont know if that changes anything. I know some of the stuff my bank's tellers do but... How can I prepare better for my first job?