I had two rounds of interviews. The first was over the phone with one member of the Account Management team, and then I came into the office where I had short interviews with the rest of the team (three others). The interviews were all fairly standard behavioral questions, and about my experience. Know your experience and know yourself and you'll be fine!
The biggest tip that my boss gave me later was that they're busy people. If they're interviewing you, that means they've already decided you're qualified. They're not going to waste their time on someone who's resume isn't enough. The interviews are about determining fit.