Changing style??

Okay I want to change my clothing style before I go back to highschool. At this point I don't really have one other than is it comfortable. I want to go back to highschool with a good attitude and good looks. I'm blonde (dyed) with brown eyes, and im 5 foot.  Like I said I don't really have a style not really into dresses and skirts. I like ripped jeans and t shirts. I'm from Pennsylvania so it's cold in the winter. I'm also 15 years old (freshman in highschool).