Grouping calls together is helpful. No physician appreciates being woken at 3:00am by a phone call and then again at 3:15am. Communication is vital so that staff have a general idea of what's going on with co-workers patients. We always do a quick walk around the unit before calling or paging, asking "Do you need to speak with Dr. So-and-so?"
Of course, sometimes things arise unexpectedly and even if you or someone else just called the physician, it is necessary to call again. You shouldn't feel bad for doing so either - that is what we're there for.
Just like any collective group of people, some physicians are just jerks and no matter what you do, they will act as such....whether on the phone or standing right next to you. It's intimidating at first, but your loyalty and obligation is to your patient, not their physician.
My personal rule is: when in doubt, make the call. I'd rather have a doctor mad at me for disturbing their sleep than to place a patient's health/life at risk. We frequently confer with one another as to whether we should call or let it wait. Ultimately however, I am responsible for my patient's health and well-being and if I feel uneasy waiting until morning or just have that gut feeling, I follow my instinct and place the call.
Definitely be prepared and be readily available if sending a page. I don't know how many times someone has paged a doctor and then leaves the floor to use the restroom or run to their locker. Understandably, the doctor tends to be irked by being placed on hold for five minutes which starts the conversation off on a bad note.
Know what you're going to say and don't be fumbling through the chart or hem-hawing around. Have any relevant computer screens up and ready so there's no waiting while you log into the system. Have as much information as possible to be able to intelligently and concisely paint a portrait for them of what exactly is going on with their patient. I've also learned that over time, most physicians develop trust in your nursing judgment and respect the work that you do (unless of course, you're calling at all hours for insignificant things that can absolutely wait until morning. That's a surefire way to get on their ****list.)