I'd suggest the "mini-Tintinalli" text book. It is a red and white soft cover book that is a scaled down version of the big text. In case you don't know Tintinalli's is one of the two "bibles" of EM, the other being Rosen's. This book is a great resource to have while working in the ED. As a fourth year on my subI's I would always keep it near by and would often refer to it as I was preparing to present my patient to my attending. This provided me with a way to check that I was addressing the major issues of the pts complaint and would allow me to anticipate some questions the attending might ask. Basically, it is a great way to make yourself look like you know what you are talking about (even when you don't!)
As far as tips for rotations go...
First remember that the ED is not the place to address all of a patient's problems nor is it a place where you need to present a full medicine-style H&P. There is a skill to developing a short, conceice, yet thorough presentation. Go over in your head how your presentation should go before you start talking. This will help you keep from rambling.
Don't be a fly on the wall. Get involved, especially in traumas/codes. In these situations, look around and find what isn't being done, and either do it or help somebody else prepare to do it. Alot of these things are usually nursing procedures in nature but they are still things you should know how to do. Like placing an IV, foley, NG or at least anticipating the need for these things and getting them ready.
Always have a pair of gloves in your pocket. You always need them at the most inconvienient times. Same with hemocult solution and a few cards. In traumas, be willing to be the rectumologist. Every pt needs one, so don't wait to be asked.
Take some time to get to know the department. Know where to find the airway equipment, crash cart, central lines, tubes, etc. This helps you anticipate and possibly get a chance at a few proceedures.
Don't lie. Say when you don't know. It can be tempting when the attending asks you if you examined this or that or if you know the answer to a specific question. I know a guy who lied about doing a rectal because he was too embarrassed to admit he forgot. He was planning on doing it after the attending asked him if it was done, but the attending asked the pt about his rectal exam before he could do so. To say the least the situation wasn't pretty. The guy pretty much lost all credibility at that point and could have failed the rotation if the attending wanted him to. Thankfully he and the attending had a heart-to-heart about it later and he was able to save some face. (no it wasn't me)
Be nice to everybody. Hopefully you would anyway. But even when provoked, always be extra nice to the nurses, techs, janitors, security, etc.
Don't bad mouth patients. Even when others around you are doing so. Remember you are being judged as a medical student and future resident.
Attend conference, even if you are not required to. Stay awake!
Get to know the PD and try to work a few shifts with him/her. Also try to get a feel for who some of the more influential attendings are. They could be your advocate come match list time as well as excellent resources for letters.
Remember your job isn't to move patients. It is to learn and to look good. Your job is to look good. Your job is to look good. You are auditioning for residency. Having said that...
Relax and have fun. Let the residents and attendings get to know who you are. You are more likely to impress people by being yourself than by trying to act a part.
I wrote this with the assumption that you are planning on EM as your career. If you are just doing a rotation, I obviously wouldn't buy the book.😀