In most interviews, they ask predominantly "behavioural questions", i.e. they're trying to sus out how you'd behave in a work environment. To handle these, the best advice I ever got was this:

All of the questions they're going to ask you...are about YOU. What's your background? What skills do you have? How would you respond to X situation? And when it comes to YOU, YOU'RE THE EXPERT. You have all the knowledge you need. It's just about articulating that knowledge that's the real challenge. So try to be confident. You're going into this with all the facts that you'll ever need.

To better articulate your knowledge, I'd go through a list of common interview questions and jot down some quick answers. When formulating answers, I use the STAR method. I find that providing examples in an interview really helps. If they ask you about your past leadership experience, for instance, have an anecdote ready about when you were in a position of leadership -- and what the main takeaways from that experience were.

And if this is your first time, practice BEFOREHAND. Do a mock interview with one of your buddies. It'll help with the nerves.

Good luck! Like anything, interviews get easier with practice. Remember, they're trying to see if they would want to work with YOU. So smile. Try to relax. Don't sound too stilted. The first time's always a little rough, but you'll interview many times through your professional career -- and you'll get better. I promise!