I modified a rear bumper of a guys car years ago with a trap door. He could pull a cable and drop hundreds of road spikes behind him. .just like in the movies. I also put a kill switch in line with the brake lights, shut off the brake light, hit the brakes so the cop rearends you and takes out his radiator. Guy was an old moonshiner that took up doing deliveries for a local organization. He wanted me to plumb oil into the exhaust for smoke, but I never heard from him after the bumper job.
Keep your car looking clean, not super shined and detailed, just a normal clean car. Make sure lights and all equipment work. Keep license and Reg up to date. Don't speed or drive erratically. It's not hard. I hate cops, but I don't get nervous around them, I like fucking with them, I know my rights and don't get intimidated easily. I also don't believe they have any authority over me.