It’s a grizzly topic, triggered by a sad story. While not common, this happens more frequently than it should and is a reminder of the dangers posed by propellers.
1) When moving the propeller, always assume it could start; keep all body parts out of the arc of the propeller
2) When the engine is running, be aware of any people or animals that approach the plane. If unsure, shut down immediately. Remember that a moving propeller can be very difficult to see; a woman in Plano is lucky to be alive.
3) Never attempt to hand prop (start) a plane without proper training of both the person turning the prop and the person inside of the cockpit.
4) Never handle the propeller with power on or keys in the ignition, unless you intend to start the plane.
5) Don’t allow passengers to enter or exit the plane while the engine is running.