Hopefully you are not applying to midwestern, otherwise you'll be my competition, but here are some tips I got from reading a few interview books.
One question that will most likely be asked is something dealing with your strengths or what characteristics you have. So, start listing traits that you have and that successful pharmacists have. For example, you might be reliable, have honesty/integrity, compassionate, have professionalism, hard working, etc. Now think of a specific example that proves that you are this type of person. During the interview, tell them your story and they'll be more likely to believe you as they have a concrete example.
I think, in this case, your examples of mentoring high school students and being involved in church are really strong points for you. As a respected pharmacist, you will be looked at as leader by others around you and as a good pharmacist, you should have a good moral foundation to base your decisions on. So those two examples can help prove that you can become a good pharmacist.
One thing in the interview books that I read that interested me is that all of them talked about body language and appearance as being very important. Make sure you are dressed very professional/conservative. Also, during the interview, avoid doing any nervous gestures, like touching your face before you answer a questions. Supposedly, people are less likely to believe you if you do this. But one of the books says "Subtly exposing your palms now and then as you speak can help demonstrate that you are open, friendly, and have nothing to hide. (This technique is used to great effect by many politicians and television talk show hosts; watch for it). Dont cross your arms, legs, or feet during the interview. Make sure to keep good eye contact with the interviewers.
Also, make sure to read up on the school beforehand. Write some questions down that you want to ask. Showing that you are knowledgable about the school and interested in the school is big plus, imo. Finally, make sure you tell them that you are interested in the school and really want to be admitted. Don't assume that they know. Don't forget to write a thank you letter for their time afterwards.
Two good books I found at the library were: "Knock 'em Dead 2004: great answers to over 200 tough interview questions - plus the latest electronic job search strategies." by Martin Yate and "Brilliant Interview" by Ros Jay.