Be calm, make your hands visible. Keeping your hands on the steering wheel and making direct eye contact will be the best!
Tell the officer what you are about to do. If they ask for your license and registration, tell them where they are, watch for a nod, then proceed with getting them.
Have a handgun on you? Tell them. Open/ concealed carry are a thing. If you have a handgun on you tell them you do, and tell them you have a licence. They will most likely ask you to remove the gun and or show your licence. See above.
Be polite. Odds are you were just speeding, have a tail light out, or your stickers are expired. Being polite and nice can take you a long way, to just a warning, a cheaper ticket, or more.
Don’t argue. The police know what the are doing, if you weren’t speeding tell it to them in a calm manner, maybe your speedometer needs to be fixed, or you were going down a hill at the wrong time. Just explain and hey, you may get off with just a warning if they understand! If not, don’t argue.
They have authority over you. You don’t know more about the law than them. Yes, speeding is a crime. No, the Articles of Confederation are not valid anymore. Please answer any questions you feel comfortable with, usually they are a simple Yes or No. No you are not a “World Citizen”. They are allowed to break your window if you are not cooperating. They are allowed to search your car if they have suspicion.
Want to surprise them? Have your Licence, registration, and insurance on you when they get to the window. Make sure you have time to grab them, look in the mirror to see how far away they are. If they see you shuffling in your car that can cause suspicion.
DO NOT, get out of your car, it may be different in other countries but do not get out of your car when pulled over unless they instruct you to. Do not try to bribe them, again another country issue, but bribing a police officer is just asking for an arrest.