What's the best way to change my appearance?

I want to change my appearence in life. I want to stand out and be unique. I dont want to be a follower and just wear what everyone else wears at school which is usualy jeans, ugg boots/flip fllops, a tshirt, and some type of sweatshirt. I would like to know whats fashionable but not too out there that i look like im trying to hard. I like to be different and I need some advice on clothes and attitude to start. (im actualy kind of immature for my age and it annoys people. Im often reminded so if u have advice for that too)