If a plane is about to crash, the first way to that comes to mind for saving yourself is to get a parachute and jump off. A helicopter, on the other hand, lacks the altitude required for a safe parachute jump. What do you do in such a scenario?
The first question is, why is the helicopter crashing? Did the engine fail? If that is the sole reason, there is an excellent chance that you will survive.
In the scenario of the engine failure, if the main rotor is turning freely, a technique called autorotation is used. For a person to become a licensed pilot, it is necessary to learn how to autorotate a helicopter. As soon as the engine dies, pilot lowers the collective. The collective determines the angle of attack of rotor blades. Lowering the collective spins the rotor while the altitude drops which results in the reduction of the rate at which the rotor is slowing down.
As soon as the aircraft gets at the spot that is chosen for the emergency landing, the collective is pulled up again that creates a downward thrust. The rate of descent of the helicopter is reduced thus preparing it for landing. You can walk off from the spot with no injuries caused.
Watch the video of a helicopter landing with autorotation.
If you are in a larger chopper, there is a good chance that it has a twin turbine engine. Failure of both the engines is quite a rare event.
In case by crashing you mean that the aircraft is damaged to the extent that even the rotor has separated, you are probably looking at one of the most horrible days of your life. The helicopter is now as capable of flying as a rock.
Depending on the durability of the helicopter, you might walk out alive after the impact.