Be at least 15min early. Be prepared. Be well groomed.
Ask questions. Be eager. My biggest pet peeve is when I ask a student if they want to go over anything, and the response I get is "No, I think I've got it down." Oh really? Because I've been doing this for over 3 years and I still don't have everything down. Along the same lines, don't be a know-it-all.
Get in there and be active and a part of the scene. If you stand back, they aren't going to pull you in.
If your crew is doing work (not related to a call), help them. Or at least offer to help them. While it's not your job, they are taking their time to help you learn. It won't hurt you to mop a floor with them in return.
After a call, ask questions about it. Look in your book and read up on it. See what you missed or try and relate it to things you've learned.
And don't be a toolbag.