What can I guy like me to do increase his chances of getting hired?

At 17 you can easily leave a 3 month job off your resume. If anyone questions the gap, tell them you needed to focus on school. But really it's so short and you're so young that I can't imagine anyone questioning. If that's the only job you've ever had, leaving it off is that much better. Make out like you're applying for your first job. A week after you submit an application, call - for every single place you apply. It's kind of a test actually. They do keep track of who follows up. Also, apply at places that more typically hire young people. At big box stores you're competing with bored housewives and 40+ y/o laid off IT guys. Prove yourself in fast-food first. Work hard, brown-nose, and learn your lesson - no filching the fries!