Before a morning of outdoor work, carry every tool you plan to use out into daylight and check each one in turn: the axe, the shears, a sickle, a knife. It takes two minutes, and in daylight each blade and handle is easier to check than it ever is on a shelf in the shed.
A sample note from a morning like this: “Axe head rusty but tight. Shears stiff at the pivot. Knife handle loose.” The last line is the one worth keeping. A loose handle is the fault most likely to cause an injury, and the easiest to forget by next time.
Next time: check the tools again after the work, before they go away, and note what changed.