Like with any new job, come prepared and on time, take notes, dress professionally, be friendly, ask your new co-workers about themselves and about the job, be upbeat and know what's expected of you when. Jobs and orientations vary, so don't assume that your experience will be bad. I was mentally prepared for a rough first year but had a great student to RN transition. My classroom orientation made me aware of hospital policies, hospital structure and who to call for help and answers when I needed it down the road. My unit orientation was great, I had a wonderful preceptor who really understood my learning style (let me try to figure it out on my own and be here when I come running with questions and need you to check my work) and my co-workers were very welcoming and helpful also. Expectations were slowly increased during my unit orientation and by the time it was done I felt ready to take on a full patient load. 9 months in I can say that I have felt competent at my job for several months. I know I'm still learning all the time and progressing as a nurse, but I can more than hold up my own patient load. I know not everyone has as a great an orientation, but it happens.
Don't be afraid to ask questions ever, your patient's care is the ultimate concern, not your pride. Know where to find policies on everything and read the policy before you go running to Nurse X to find out what they do. It's helpful to know how different experienced RNs go about things, but ultimately it's the policy that you should go by and that you'll be held to by your manager. It also looks better if you've at least tried to find out the answer on your own first.
On a personal note, leave work behind you when you leave. Keep up with your friends, talk to your nursing school friends, get exercise and try to eat well. You'll eventually find time to pee/eat/drink again, but try not to give yourself a UTI in those first weeks on the floor.