How to act more preppy, but still being myself? PLEASE ANSWER, thank you.?

So, I'll be starting 7th grade in about 1 1/2 months, I'm SO excited. But, the thing is I wanna be more preppy... during my 6th grade year I was more of a jock. Since I'll be in 7th grade soon, I wanna start a new year with a new me. Any advice, please ? c: