How can we "grow up" our styles?

[signs_of_poetry]

My friend and I are both 19- 20 in a few months. We've improved our styles a lot since we first met at the age of 14 (he used to wear Aeropostale hoodies almost every single day), but we want to grow our styles up a bit. We both want to keep a bit of "youth" in our looks since we are still young, but we want to look more polished and defined.

We both like some of the more 1970s urban feel from Urban Outfitters, and I am big into styles from the 1950s, but we also like some touches from modern fashions.

Any tips to go from our teens to our twenties in style?

We're a guy and a girl.