Here is a video about taking precautions while hand-starting a prop engine:
In this video Bob Tait recommends treating a prop at all times as a 'loaded gun' regardless of magneto and master switch positions: faulty wiring, undetectable by the operator of the aircraft, could cause a magneto send a spark to the plugs if the prop is turned.
. Sound advice.
My question is, when it's required to hand-rotate a prop a small amount, for the purpose of attaching a tow-bar, dressing the prop, for close parking another aircraft's wing in a small shared hangar, or inspecting an alternator belt, how should this be done safely if the prop is potentially 'loaded'?