Do your research. The more you know about the university you are applying to and the program of study you are interested in, the better. The university representative interviewing you will, almost certainly, ask you why you are interested in that university and why you want to study there. The more detailed and specific answers you can give, the more the representative will see your commitment to studying at that institution.
Do practice interviews. Being prepared for potential questions from the interviewer can make you feel more confidant about your interview as well as assure that you answer the questions the best way possible. Ask teachers, your parents or a career adviser to help you prepare for the questions that you might be asked at your university interview.
Know what is going on in the world. The interviewer will likely want to asses how up you are on current events. Watch the news and read updated publications on the days leading up to the interview to make sure you are current.
Prepare your own list of questions. The interviewer will ask you if you have any questions and you want to be sure that you do. You can ask specific questions about the program you are applying to or more general questions about the university. Be sure to ask well-informed questions as well as questions in which the answers are not commonly known.
Dress the part. Be sure to look your best on the day of the interview. Get plenty of sleep the night before so you are well rested and dress up for the interview. Your first impression says a lot, so your clothes should be ironed and well put together. Also, don't chew gum or wear heavy cologne or perfume that could be potentially distracting to the interviewer.
Follow up. After the interview, you want to thank the admissions officer for her time by sending her a thank-you letter. Express your gratitude to the representative for taking the time to meet with you and reiterate your continued interest in that university.