Most Helpful Guy
It's genetic and you're born that way, so it's not much to do. But it takes longer time before you looks old and when you gets older you may enjoy the youthful look more. But the only few things you can do is avoid wearing pastel colors and childish colors like pink. Try rather to dress mature and in mature color. Marine blue, black, white and gray would appear more mature. Playful colors won't. Your behavior and vibes would also influence how mature you appears. Although you dress mature and wears makeup, it would still not change your facial features that much or height.
Most Helpful Girl
Wear professional clothes.. no one will think u are 16.