Chill the onion in the fridge or freezer for 10 to 15 minutes before cutting
Use a sharp knife
Cut near a running fan or under a kitchen vent
Keep the root end intact until the last cut
Cut the onion under cold running water
Wear onion goggles
Peel the onion quickly and cut it promptly
Use a very sharp, thin blade to reduce cell damage
Slice the onion from the top down, not through the root first
Chew gum while cutting
Light a candle nearby
Use a food processor or slicer if possible