The most important things are to get identifying information from the other driver(s), identify the other vehicle(s), notify the police and take photographs. Get the names, addresses, telephone numbers, driver’s license numbers and insurance information from all the drivers involved in the accident.
Write down the license plate number and the make, model and color of all the vehicles involved in the accident. Be polite and try to avoid discussing how the accident occurred or arguing over who is a fault with anyone involved in the accident.
If the police indicate they will investigate the accident, try to leave all vehicles at their point of rest until the police arrive. This will give the investigating officer an opportunity to document what could ultimately be important details about how the cars collided. If it is not safe to leave the cars where they are or they create too much of a traffic block, move them to the nearest point of safety. The police will probably interview each driver separately.
Make sure to give the officer as accurate and complete information you can. Stick to the facts; don’t guess, speculate or assume things you don’t know. Avoid insulting or disparaging the other driver, even if you believe his or her behavior in causing the accident was outrageous. It won’t make you look any better later on if your tirade winds up on the traffic collision report.