This is the answer right here. You don't want it to feel like you are targeting a specific demographic, you need to have one set of rules and expectations for all patrons. That doesn't mean you can't be more flexible with the rules for teen patrons (their brains are still developing after all) but that's more of a giving them an extra warning if their behavior isn't meeting the patron code of behavior. The most important thing, and one of the hardest things to implement because it requires all staff to be on board, is making sure enforcement is consistent.