Call the Local Police or Highway Patrol.
The police report will document how the accident occurred and will have the officer’s opinion of who was at fault. Generally, it will also contain certain information about the other driver, their vehicle, and their insurance company. Having a police report will also speed up the insurance claims process.

What Not to Say.
First and foremost, always be truthful with any investigating law enforcement officer. Keep in mind however, if you speak to the other driver or witnesses and admit fault, or if you simply offer a friendly apology for causing the wreck, it can be used against you later. You simply do not need to volunteer this type of information. In fact, it is possible that you may think you are in the wrong but later learn that the other driver is as much or more to blame than you are.

Driver Information.
As mentioned above, this information will be contained on the police report. If there is no police report, it is important to obtain certain information from the other party, including the name, address, phone number of the other party, their license number, the make and model of their vehicle and their insurance company name and policy number.

Witness Information.
Do your best to get all of the names, addresses, and telephone numbers of any witnesses at the scene. Later, these people may be able to help you if the other driver “disremembers” their role in the wreck or disagrees with your description of events.

Photographs.
Most people have cameras on their cell phones. You should take photographs of all cars involved immediately after the collision, as well as the roadway or scene of the wreck. If you have any signs of physical injury, such as cuts or bruises, take photographs as soon as possible. If your injuries are the result of a slip/trip and fall, getting photographs of the scene is very important.

Seek Medical Attention.
Most importantly, if you are injured, then you should get medical treatment immediately. Delays in seeking medical treatment permits insurance adjusters to argue you were not really hurt.