I'm trying to be preppy, any suggestions?

Okay so this year will be my freshman year and I wanna be different. I have some AE, A&F, HCO, and Aero clothes but not more than like ten shirts and some jeans and shirts. I wanna know how to act preppy and look it. But I don't wanna be stuckup. Btw, I'm 13 so nothing too extreme. (I know I'm young. I look 15 or 16 though)