i did an externship recently (i'm also a noob 2nd year). here's what i learned.
1. Constantly be engaged in what you are doing. If you are observing / scrubbed in to the OR, pay attention and be an active learning member of the team. even if you are merely observing a procedure, consider asking pertinent questions to the residents to gain a better understanding. With that said......
2. Don't ask stupid questions. If you are observing a procedure, techniques, etc, really think about a question you may feel compelled to ask. Considered 2 things: (1) the content of your question and (2) the manner in which you articulate the question. Both of these reflect your knowledge and professionalism to a degree. Yes, you are externing to learn, so ask questions to gain understanding - but you should discern between good and bad questions (sorry i dont know how to be more specific - just think about everything you say and ask before doing so )
3. Ask if you can help!! if you find yourself standing around, immediately stop and ask a resident if there's anything you can do to help them. Standing around is not only a waste of your time but it makes you look like an idiot.
4. Try to find out what is going on the following day the day before (verbage?) so you can read up on the procedure. it will make it more enriching and make you look good in case you get pimped
5. Should be obvious, but be incredibly professional, diligent, and ON TIME.
6. Find out the dress attire you need to be in. If you are going to be in the OR all the time, then they'll provide you scrubs. But if, for example, you will be spending time in a clinic or at a faculty practice, consider professional attire (shirt & tie) with your student white coat. I found myself in what i perceived to be an awkward position in the faculty clinic when my noob a** is wearing a white-coat and scrubs (we were in the OR earlier) white the residents and attendings were in shirt/tie/whitecoat. Retrospectively, i would have worn a shirt and tie every day because either way, if i was in the OR they give you hospital scrubs, if I was in clinic i looked professional.
if i think of more i'll post.