Buy River's Review for the boards - make that your first book as an intern and read as much as you can from cover to cover. Use this book as an outline and throughout your residency, add things you didn't know (from Tintinalli's and Rosen's) into the appropriate sections of the book. Buy Peer V and VI and read them cover to cover each year before the inservice. By the end of your residency, you will have read River's twice, you will have your own personal reference book, and you will do very well in the future.
Be sure to find the time to keep a life during intern year - it is very easy to lose yourself if you get too caught up in the medical world. Most important - HAVE FUN! Think of next year as a year to remember fondly and proudly, not as a time to get through and remember with disdain...
Keep great relationships with the off-service residents - they will either help or hinder in your future.
Be mindful of every interaction you have with everyone you see in the hospital (patients, nurses, attendings, residents, orderlies, janitors). You never know who else is listening (or watching) and as an EM resident, you are under more scrutiny than any other resident to get along with everyone - that will be the single most important determining factor of your success in this field (yes! - above your clinical knowledge).
Relax, show up early, stay late. You will do just fine!