Today I chatted with a USC admission officer a little bit. She mentioned what she would be looking for when she does interviews with applicants. Some focal points are:
1. Career goals - It's not what exactly your goal is but the story behind that goal that truly matters. The majority of applicants pursue a finance-related career goal, so from adcom's viewpoint their goals are just the same. As a result, the difference would lie in how passionate the applicant is about his/her goal.
2. Personality - Just be yourself when you do the interview. The job of each school's adcom is to find people who can fit one another and work effectively as a team. The desired type of personality, however, differs from school to school. USC loves easy-going, altruistic people, fyi.
Also, adcom understands that career goals may change when people are exposed to more stimulations as time goes by. So don't be afraid to be flexible. Don't force yourself to insist that what you say during the interview should be some kind of promise that locks your future direction. Be relaxed during the interview.
Hope that helps
