How to Be More Polite When Speaking English

Many students' pitch is already a little too high out of feeling nervousness or uncomfortable speaking English. They may notice an American speaking really high and be like why are they speaking so high? Some Americans also I think their pitch goes up someone they're nervous. So actually I would say that would be a good tip for an American who's trying to figure out how to be more polite but for a non-native speaker I don't think I would necessarily say that.