I prepared for my interview by making sure that my resume and cover letter were up to date. I had a feeling that the interviewers were going to ask me about past experiences, so it's best to have your resume current and know they are going to ask about your past.
I also prepared by keeping a mental list of three positive work-related qualities and three work-related improvements at the back of my mind. I have not been to an interview yet where they haven't asked me about positive qualities as well as things I am trying to improve about myself.
Finally, do your research on the facility! Know what the hospital is good at, look up their core beliefs. Have an idea of what kinds of things happen on the floor you are applying on. If you disagree with what the hospital has to say, then you know right away that it might not be the best place for you to work.