What are some tricks used by police officers that most people never notice?

It’s not really a trick, but one tactic I commonly used when I worked traffic was to set up and run radar or Lidar a short distance from one of those roadside stands that warn drivers of their speed. Not surprisingly there are people who speed up when they see those things never suspecting that a cop might be sitting just down the road a bit. If I caught someone who just passed one of those stands the only way they were likely to avoid a ticket was if they were about to be giving birth or rushing to the hospital on some other obvious medical emergency since that roadside radar stand already gave them their warning.