Just be yourself. If you don't know something they are asking, don't make it up. Just politely say, "I don't know the answer to that but will be willing to research and look it up." Know why you want to go into the CRNA field and what you have over the other candidates interviewing. Don't be overly confident though! Depending on the school you are interviewing at, there may be a mixture of questions. I was asked mostly personal questions but also got 3 math questions and a clinical question about the mechanism of action of a drug and what receptors this drug works off of. I sat at my dining room table and practiced over and over again as if I were in the real interview. Good Luck!