I had three interviews: one over the phone with HR, once with my hiring manager and a hiring manager from another team (she previously worked at the company I was leaving), then another with the hiring manager and the Director of the team I was a member of. Basically, you need to act professional, bring a few resumes, a pad of paper and pen to jot notes on, and remember to ask questions that will help you decide if it is the right job for you.