If you borrow a pocket knife and it is handed to you open, you must hand it back open and let the person who loaned it to you close it, or if it’s closed when you get it, close it before you give it back.
If I find a penny that’s tails up, I don’t pick it up. I kick it to try to turn it over so someone else can have good luck. 
Pearls at a wedding mean tears (but I’ve never been to a wedding where the bride didn’t have pearls somewhere, including my own wedding.)
Opals are bad luck unless they are your birthstone (October.)
Don’t walk under a ladder.
Don’t open an umbrella indoors.
It’s good luck to eat black-eyed peas and ham on New Year’s Day.
Tri-color cats are good luck. (I think that one comes from Japan, where I was born.)
If your initials spell a word, you’ll have good luck.
If your right palm itches, you’ll shake hands with a stranger; left palm means you’ll get money. OR, according to my co-worker, left hand means you’ll give away money and right means you’ll get it.
If you spill salt you must toss some over your left shoulder to ward off bad luck.
There’s more where these came from. If it matters, I live in rural central Florida. And just so’s ya know, I don’t believe any of them, but think they are fun to observe anyway, as long as you don’t get weird about them.