Step 1
At the scene
In the first minutes after a crash, your job is to stay safe, get help on the way, and capture what you can — because the scene disappears fast and you will not get a second chance at it.
Check yourself and everyone else for injuries before anything else, then move to a safe spot if the vehicles are creating a hazard. Call 911 — even for a minor crash, having an officer document it creates the neutral, on-the-record account your claim will later depend on.
While you wait, photograph everything: both vehicles and their positions, the damage from several angles, the road, traffic signals and signs, skid marks, debris, and any visible injuries. Exchange names, phone numbers, insurance details, and license plates with the other driver, and get the names and numbers of any witnesses before they leave. Write down the time, the weather, and exactly how it happened while it is fresh.
What you should not do matters just as much: do not apologize, do not admit fault, and do not speculate about what happened. A simple "I’m sorry" can later be treated as an admission of liability, even when the crash was not your fault.