Do digital submission, if you can.
I would highly recommend doing this because you get to do takes over and over until they're perfect and see what you look like on film. Despite it being a screen audition still act as if you're on stage so don't tone down your movements as if you're doing screen acting.
Looking for contrasting monologues
The best ons are not popular at all so the admissions team can see you as the role rather than contrast you to an actor who made the monologue famous.
Play within your age range.
Credibility is a big part of acting and looking the part makes it that much easier. Also you may find it easier to relate to and portray teenage angst than the struggle of a single mother.
Interview tips
Be passionate about whatever you're talking about. Get good at improv because you have to answer the questions on the spot. Look over your college essays because a lot of the questions relate to app questions about your interests and identity.
Acknowledge humanity
Both you and your admissions counselors are human. So are all the actors in the world. Don't be nervous if you don't have as much formal experience as you think you should. Let your humanity shine through and know that you did your best.