How can I prevent acne?

I don’t have acne and I do not want it. AT ALL! In fact, I’m terrified of getting it! So I want to know some things that will help me prevent acne on my face. I don’t want to go out and buy anything because if it’s like a cream or something my mom won’t approve. So please help me. And I’m not allowed to buy the netrogeno(or however you spell it) wave either. Just please stay the heck away from buying something. Just make it some things I can do at home. And nothing that will break my face out because obviously that isn’t what I want.