How do you change your style?

I'm almost 19 years old and I want mature a little bit... My style isn't really of any particular "category" but most of the time i wear skinny jeans, Osiris shoes... i also have etnies, vans and DC, i also wear graphic tee's mostly black... i want to dress more colorful and more "girlish" but not frilly... i have a hard time with it because im most comfortable in this attire but i want to look more open and friendly not... heavy eyeliner, black... black.... black..."leave me alone" type stuff, how do you change?!