How to interact with a police officer(s)

I think it's all simple really ~ lets stick with getting pulled over: first and foremost, they know who you're supposed to be long before they approach you, so if you don't match the description or there is anything "hinky" going on in the cops mind, then he/she will already be on edge before they've said a word to you. They are doing their JOB and much like yourself, they just want their day to go as smoothly as possible so they can go home at the end of their shift. Cops are human, this means they have all the same crap in their lives that you do ~ bills, taxes, kids, moms, dads etcetera etcetera.
No matter what, if you're getting pulled over, there's a reason. You should immediately be on high alert and ready to do whatever is needed to get the situation resolved and over with without conflict. Some cops are just bigger assholes than others (pretty common in "civilians" too last time I checked) ~ accept the fact that for at least the next 10 minutes you are not in total control of the situation, but you do have the ability to control it's outcome to some degree.
You know who's afraid of the police? People who have done or are doing something wrong. Cops are trained to deescalate situations, but if you are going to insist on escalating ~ they are trained for that too. How it ultimately goes is way more about you than most people realize.