Just act like the cops best friend jeeez. Ask him how his nights going, act like he was your neighbor.
When you show a cop that you don't fear them, Act like your glad he's doing his job. And remember that, this guys worst fear is a traffic stop that turns deadly. If you think about it in terms of, He's just as scared walkin up to you, You'll realize cops calm down a good bit when they see you as cooperating.