Absolutely key advice here. Especially from geekgirl and Mango.
A few related thoughts:
1) When you're cross-covering, once the major fires, consult hammering and OR time have passed, routinely ROUND on patients you don't know. No matter what hour it is. Don't assume that because you're not being paged, all must be well. Just two weeks ago, when I finally got to my rounds at 12 am while acting as nightfloat at a community hospital, I noticed that a patient s/p gastric bypass had been tachycardic since the OR. No one had called me about her, and the resident who passed off to me had said, "no need to worry about her, she's fine." When I went into the room, she was unresponsive to sternal rube, with an O2sat of 45%.
2) As much as the silly pages make you want to tear your hair out, RESPOND NICELY when nurses page you. Don't groan & gripe. Deal with the question politely, and remain in that nurse's good graces, so that when something urgent DOES happen, she won't hesitate to call you. Hearing about 10 nonurgent issues at a late hour is a thousand times better than missing the page that could have saved a patient, which never came your way because the nurse didn't want to deal with your attitude.
3) Be vigorous about repleting electrolytes. You'll avoid many cases of Afib and trips to the ICU if you think about a patient's potassium after he's had 24 hours of diarrhea.
4) It's been mentioned before, but I'll say it again: See the patient yourself! Even if an order seems routine, don't just agree to it without seeing the patient. Examples that have happened to me recently:
Page: "Can you please give me a one-time order for ativan? I think this patient's having an anxiety attack."
Actuality: Pt had just thrown a PE, was tachy to 130 and had an O2sat of 70%
Page: "I think Mr. X needs a breathing treatment. He's saying he's short of breath."
Actuality: Pt had an SBO, was massively distended, and in dire need of an NGT
5) Serially round on your sickest patients. This is a scenario when being compulsive is to your advantage. You can never be too diligent.
6) COORDINATE with the services you consult, don't just sit back and assume they'll take care of everything. If, 6 hours after receiving the digoxin dose that cardiology recommended, your patient's HR is still 170, clearly you need a new plan. Come up with one, call the cardiologist back and see if he agrees. If he doesn't call back, implement it if you think it's the right thing to do (when you're an intern, talk w/ your senior about this first).
7) Look at all films & CT scans on your patients yourself. Don't just wait for the read. Better yet, after you've reviewed it on your own, walk your keister down to radiology and review it with one of the experts. There will be times when your ability to pick up basic features on a film will be important to timely management.
8) As an intern, when you try to study/ prepare yourself, tackle the things that scare you the most. Know ACLS inside and out. Study the basics of ICU care - when you've given 1 L of crystalloid on the floor and your patient's blood pressure is still 70, what's the next step? Breaking down the frightening scenarios into discrete steps will take away some of the panic and keep you clear headed about what to do. You'll always have a senior as a backup to help you through the worst parts, but the knowledge that you could at least get the patient to the ICU and stabilized WITHOUT your senior, will leave you feeling a lot more comfortable in urgent situations.