Back up only minimal distances. Reduce speed on slopes and when making sharp turns to prevent tipping or loss of control. Watch for rocks, holes and other hazards. Mow only in daylight. Stop and inspect the blades and shaft if the mower runs into a rock or stump.
Damaged blades can cause vibration and vibration can loosen the blades.
Check the blade-mounting bolts frequently for tightness. Check grass catcher bags for wear. Replace worn bags. Do not use a lawn mower when the ground is wet. Do not operate a lawn mower barefoot or wearing sandals.