You hear the blare of the siren and see emergency lights flashing in your rearview mirror. You realize you are the point of interest of a police officer. What now?
Pull over safely the first opportunity you have, utilizing your turn signal.
Once safely pulled over, put both hands on the wheel and sit still. Never get out of your car unless the officer asks you to.
Don't rummage through your glove compartment looking for registration or insurance cards, or through your back pocket to retrieve your wallet. For police officers, NO traffic stop is ordinary. They may believe you're reaching for a weapon. Don't fetch the license or registration until the officer asks for them.
Avoid giving the police officer a reason to search your vehicle. If the officer observes you trying to hide something or chuck something out the window, he may conduct a legal search. If the officer has reasonable suspicion that you are armed, you may be frisked. If you or a passenger gives the officer probable cause that your're up to no good (criminal activity), they're free to search your car and any passengers.
An officer may also seize any illegal objects in "plain view," such as drug paraphernalia or beer bottles. If these things are spotted, the officer is allowed to enter the car and search to his heart's content. Your car may also be searced if you or a passenger is arrested.
Finally, do not initiate any dialog with the officer. Let him speak first. Answer politely; don't make demands; don't argue; and be brief and noncommittal with your answers. A friendly officer may appear open to leniency if only you'll give more in-depth information. Don't fall for this. What you say - or don't say - can be critical if you contest the citation.