I assume you will dress professionally, etc., smile, look the interviewer in the eye ocassionally, etc. -- all those things that go along with any interview. So, I won't waste time with those things. I mention them only because some nurses and nursing students think "that stuff only applies to other people -- not nurses," but that's not true. It always helps to make a generally good first impression.
1. Type up a good resume and take a few copies with you to give to the interviewer. Never "embellish" a resume, but state you past experiences and education in a positive way. Be prepared to discuss those positions, why you liked/disliked them, and what you learned from them.
2. Be prepared to answer some basic questions, such as "Why are you interested in this job?" and "What about our hospital and this particular unit interests you?" Hopefully, you will be able to discuss the characteristics of the hospital and of that particular unit's population that interests you. No one wants to work with someone who is there "just for the money" or "just to have a job -- any job." Demonstrate some real interest in the type of work they do!
3. Think through some answers to other probably questions, such as, "Why do you want to be a nurse?" "What type of nursing are you interested in?" "What have you enjoyed most/least about nursing school?" and "What are you major strenghts and weaknesses?" Again, with these types of questions, the interviewer is probably not looking for one specific answer, but is trying to get to know and to see whether or not you have a lively mind. Are you self-aware? Do you notice the things around you and think about them? or Do you just go through life doing what you have to do and not much else? In other words, is the light-bulb turned on inside?
4. Ask them some questions. You should probably prepare a few questions in advance to ask -- but it is also good to allow questions to arise naturally as part of your interview. This shows that you are really "interacting with" the interviewer, having a real conversation rather than simply answering questions. Questions you might have prepared in advance might involve the types of patients on that unit, the responsibilities of the position, the skills that you will get to practice, the orientation to the position, typical schedule, etc. It's OK to ask about salary, but put that until the end so as not to suggest it is your primary interest.
If you can demonstrate that, yes, you have a lively mind as well as a genuine interest in the type of work that they do, then your chances of getting the job are good. If not, then the job is probably a bad fit for you in the first place.