Pretty good advice so far...
1. Be agressive about learning bedside procedures. The pgy-2s and 3s will love that you can put in central lines unsupervised. (Plus it's fun.)
2. Read early and often. Read a little every night about anything. Don't restrict your reading to whatever rotation topics you happen to be learning about during the day. This keeps things interesting while still allowing you to pick up a broad range of info.
3. Call an upper year if you need to. But don't be afraid to make decisions. Better to make decisions and be wrong occasionally than to rarely act independently and get in the habit of reaching for the phone every time a problem presents itself. (Unlike the above poster, I do order CT scans without anyone's approval when they are indicated... I have never been chastised for it either.)
4. You WILL get screwed with the worst holiday schedule, the extra call, the crap jobs that no one likes doing, the extra paperwork, the stat discharge summaries... OK, maybe not always, but if it comes down to you wanting vacation at the same time as the pgy-2 or higher, guess who's going to get the vacation? Don't whine. Take it in stride, and realize that no matter how crappy you think intern life can be, the guys who came before you (before the 80 hour week) had it much harder than you do.
5. Don't take **** from people just because you are an intern. If you make a management decision based on sound reasoning, defend it. Sometimes upper years and attendings push you just to see if you know why you did something. Sometimes they just want to f*** with the intern.
6. Nurses can teach you a lot early on. Be nice. But don't be afraid to lay the smack down once in a while if they get lazy on you, or start trying to convince you why you shouldn't order tid wet to dry dressing changes on a patient.
7. If you're gonna lay the smack down on a nurse, yelling and screaming at them is not the way to do it... for a number of reasons. The best way to do it is to just take their name down, ask the charge nurse for an incident report, and take 5 minutes to fill it out right there at the nursing station in front of everyone. Or, if you are away from the floor, page the nursing supervisor and tell her your story. I once had the nursing supervisor go to the floor and start some IV fluids on a patient because the floor nurse told me she was too busy and hung up on me. I never again had another problem getting telephone orders carried out on that floor.
8. Go out and have fun as much as possible. I will go out during the week for an hour or so, have a single beer, and see some good music, or hang with some students/residents/fellows. Sure, I get a little less sleep, but it makes life a lot more bearable when you have little breaks in your routine. If you don't do stuff to break up the routine, you can go weeks or even months where the days just blur together and you start to get strung out. (Yes, I speak from experience!)
9. If you're gonna go to the OR and do a case, PREPARE for it. I bought Skandalakis to review cases the night before, and it makes cases MUCH better when you know what steps you are supposed to do. You can take charge, and you'll know what instrument to ask for and when. Not to mention, cases are way more relaxing and high-yield when you know what it is that you are trying to do. Though sometimes you don't get any time to prepare, and you just have to wing it!
Good luck.