How can i take steps to become more outgoing, friendly, and just a better person?

Im 15, and a freshman in highschool, and this whole year has gone by so fast and its really made me realize how much im going to miss highschool once its gone, so i want to make the best of it while i can. This whole year not alot of people have thought too highly of me, alot of guys and even more girls dont talk to me cuz im just known as a "stupid druggie" and alot of people think im stupid and mean. I got caught smoking pot with my girlfriend a week ago, and its made me realize that although its fun, the consequenses arent worth it. Im quitting now, and when i tell people they laugh. I guess its be nice to have advice on how to change the way people think of me. My friends are all known as stoners too, and i know if ppl see me with them theyll never believe i quit, but i dont want to ditch my friends because, well, theyre my friends and i love them. I started taking an antidepressant and its made me more talkative and friendly then normal and 2 "jocks" actually think better of me, and it makes me want to make the next 3 years of highschool the best.