When you have a car accident, it is important to take a few minutes to assess the situation and know what to do next.
If anyone is injured, call 911 immediately. If the car is drivable, move it to the side of the road. If not, stay in the car until help arrives.
Obviously, you should always be aware of your surroundings when driving. But even the most cautious drivers can be involved in an accident.
The best way to prepare for such an event is to know what to do beforehand.