Most Helpful Girl
It depends on how you carry yourself. If you carry yourself in a mature manner it shouldn't be an issue.
I would, however, refrain from wearing clothes that have brands written across them- Pink, Aeropostale, Abercrombie, etc, as they tend to make you look younger.
Really piecing together your outfit- jeans, shirt, sweater/blazer/jacket, and throwing in accesseries will keep you looking your age.