I feel ya bro, I'm 17 and a junior. I found one things that's normally gets a conversation going, music, almost everyone enjoys it and listens to it. Sometimes you listen to completely different stuff, but it still starts the conversation. Honestly, I'm not good looking at all, but I'm polite, funny and outgoing. Girls like that kind of stuff, especially when you're confident in yourself. There is a difference between cocky and confident and you gotta watch that. If you're humble that gets rid of cockiness. When you show people you're truck you can say "yeah I built this" and show your pride, just don't be like "this is the best truck here." Also I don't know how big your high school is, but if people know you by your truck, offer them rides home and to the store and what not. That shows the confidence. Hope this helps.