Get yourself an ER related pocket resource book. The one I have was about $20, and is called Emergency Critical Care Pocket Guide, ACLS version. There are other more expensive ones, but this one is fine for me.
You can take a drug book, but it will be easier if you have a PDA with some good drug programs. Epocrates is free to download and there are others you can buy. You have lots of quick drug info at a glance. You can also have drip calculations, etc instantly. In the ER you don't always have the luxury of flipping thru a resources book.
You can get a good PDA with 32 mg RAM for under $200, very well worth the money!
Don't be afraid to say, "I don't know but I can find out", and do it! Keep a small notebook with you, pocket sized, and when you get little pearls of wisdom, write them down. I also keep a pocket calculator with me, it is quicker than the calculator on the PDA. I also keep a little cheat sheet taped into the door of the calculator that has common names of intubation drugs, some docs may ask for Sux and some anectine....they are the same drug. Same with pavulon and pancuronium, vecuronium and norcuron. This will save confusion when you need things in an instant.
When you are in your first code, pick one place to be an observe all you can. Or place yourself in a position to push drugs, or hand drugs from the cart, or record. Don't try to do everything. Stay in one place and learn that area well, but watch everything and learn. Stick around for the post mortum care. You will learn a lot by asking questions at that time.
Realize that most emergency dept patients are NOT emergencies, and will not die if you do not jump immediately. In reality if you did not care at all to most of them in an entire shift, they would not die! They might be miserable, but they will not die. Do what you can when and where you can. You can not start 3 IV's at once, but you can prioritize who gets one first. Keep commonly used IV supplies in your pocket, i.e. alcohol swabs, tourniquets, extra catheters, Yes, your pockets get full! I like the cargo style scrub pants, because of the 2 large pockets on the sides and still use my scrub top pockets for other stuff. Once you decide what goes where, put everything in the same place every time, and you will not have to fumble for things.
Also realize that even the most experienced nurse will have questions about certain things, so don't be afraid to ask questions. I worry about new grads who think they know enough rather than those who are a little insecure. If you are not insecure, you are probably dangerous.
Most of all, try to enjoy the adventure. You will see things people in other walks of life can not even imagine. You will see the best and worst of humanity. You will see situations turn on a dime, so be ready. Never take anything for granted. The little old lady who looks sick but does not complain is usually in much worse shape than the ones who scream, yell and demand care. Watch out for the quiet ones, they will come back to bite you on the butt!
Good luck, you will be terrified much of the time in your first year, don't worry, they can kill you, but they can't eat you!