First...STAY CALM. When I was a new grad in the ED, I was a basket case. The nurses used to call me "Starbucks" because I was at top speed to the point of almost shaking all night long like I had 10 too many lattes before work. Haha.
Second...LISTEN to your patients. Many times they are on point. Do you remember learning about feelings of impending doom? If a patient tells you they are going to die, they are probably right. Stay on top of them. I have seen this many times and it's so creepy.
Third..like others have said, find a mentor. Ask questions when you are unsure.
Most of all...have fun and keep learning. I learn something new everyday. Learn from your patients, the ED techs, other nurses, doctors, everyone around you.
ER nursing is fast paced, dramatic, fun, funny, sad, joyous, scary...ever changing. BE FLEXIBLE, BE READY FOR ANYTHING and EVERYTHING.