Obviously the most important thing to do after you’ve been in an accident is get appropriate medical care. Are there legal issues, sure, and I’m going to address them. But if you’re bleeding or if you have a concussion or you’re dizzy, or worse, obviously you want to worry about your health and getting your health taken care of before you worry about the legal issues.
If you aren’t injured too badly, and if your passenger is or your friend is, and they’re being taken care of medically and you have time to take care of the legal issues, one very important thing is to get the names of all the witnesses who are around there: business cards, names, email contact, cell phone contact. Because, if the policeman is in a hurry they might talk to one witness but miss three or four.
The other thing you want to do, if there is no police office there, is make sure–assuming this is an automobile accident–that you get the license plate of the other vehicle and ideally the driver’s license and other information on the driver.