Knocking on wood
Blowing on dandelion seeds
Using a fallen eyelash to make a wish
Kissing under mistletoe
Throwing spilled salt over your left shoulder
Don’t put shoes on the table/bed
Don’t open an umbrella indoors
Finding four leaf clovers for luck
Carving jack-o-lanterns
Wearing masks/costumes on Halloween
Using flower petals to play ‘Love-me, Love-me-not’
Wishing on a falling starThat’s all I can think of at the moment, add more!