How can I look older ?

Im a 14 year old boy, i look about 13, I want to look about 16 ? :) I'm about 5.2 with brown hair, shortish at the back and longer on the front and sides, I have pubic and underarm hair but no facial hair. I have freckles and rosy cheeks which i think make me look younger, any way to get rid of them ? Just interested in general ways to look older, btw I buy my clothes in Primark, Topman, Burton, Republic, Hollister and shops like that mostly :)