I get this question from time to time, and it's a good one:
How do I interview well if I'm an introvert? It takes me a while to warm up to people, and I don't have a naturally bubbly personality. Will I be at a disadvantage?
No. You'll interview just fine. The key to nailing your interview is not to give a drama club worthy performance, or to share everything from your favorite toenail color to how you felt about your breakup last week. Keep in mind, a college campus overrun with extroverts would be just an undesirable as one with without any of them at all.
The key to nailing your college interview (and, by the way, every interview you do from this point out) is to practice. Figure out what the three things are that you want your interviewer to walk away from the interview knowing about you. Make them as specialized as possible and make sure you have proof. Are you a very empathetic person? Exceptionally determined in the face of adversity? Creative at solving difficult problems? Write your list, and then back it up with a story. Interview questions are often open-ended.. Find a way to get your point across.
Practicing the interview and going in with a game plan will get you into your comfort zone. Don't rely on yourself to ad lib. As an introvert, a road map of your story should get you comfortable with what you are going to say. Neither an introvert nor an extrovert interview well if they are unprepared. Several interviews come to mind with bubbly students who obviously did not practice, and ended up interviewing poorly in spite of their personal charisma.
One more caveat: Be sure to make the interview a conversation. If you are nervous, it is easy to fall into the trap of recitation. Make sure you are engaging with and reacting to your interviewer - she is not an audience, but a person. Ask a few questions. Laugh at a joke. Respond to her enthusiasm for a specific subject. Don't get sidetracked by this, but don't let the opportunity to connect slip.
If you need a mantra, let it be this: The interview is not about charming the pants off your interviewer. It's about communicating clearly and well what it is that makes you different and sets you apart.