Why are you nervous, everyone has to start somewhere. Every one on here was a novice at some point, and every one of us are still learning, we are all also learning continually, none of us are the best hairdresser ever, as that person doesn't exist, yet we still strive to be the best we can.
Best advice I have for your Saturday job is be confident, and ask questions, be prepared to work until your feet are hurting, and talk with clients, get to know them.
Best of luck in your education, soak it all up, and enjoy it all!
To the other poster, keep trying, there will be a salon out there willing to give you an opportunity. Offer to do free work on weekends, it all adds up. And as many will tell you, there is no substitute for the real thing no matter how well run and presented a college salon may be, it is just that, a college salon where people don't have to keep a job, where as a salon is a completely different environment with different but better rules xoxo