It's hard to guess what might impress someone else. It's easier to just be the person you'd be impressed with.
If you're building a college counseling business, build the one you'd want to send your own children to.
If want to run for president of the Key Club someday, start by being the member you'd want in the club if you were already in charge.
Be the player you'd want on the team if you were the coach. Be the student you'd want in class if you were the teacher. Be the musician you'd want in the first chair if you directed the jazz band, the worker you'd hire if you were the boss, or the volunteer you'd want dedicating time if you ran the non-profit.
If you can be the person who'd impress yourself, chances are you'll impress colleges, too.