If one walks underneath an open ladder it is said to bring bad luck. Sometimes it is said that this can be undone by immediately walking backwards back underneath the ladder.
105
An acorn should be carried to bring luck and ensure a long life.
115
A single magpie is considered a sign of bad luck. A Guide to the Scientific Knowledge of Things Familiar recites an old proverb concerning the incidence of bad weather when magpies forage alone and a possible scientific explanation for this.
49
Before traveling a person should, apparently, sit on their luggage. (Russian)
117
In Asia, the digit 4 never appears in any Nokia handset model number, because 4 is considered unlucky in many parts of Southeast/East Asia.
78
An acorn at the window will keep lightning out
93
Placing a hat on the bed is, apparently, bad luck. (South Carolina)
9
When you speak of bad luck, it is said that one should always knock on wood. Also knocking when speaking of good luck apparently helps with having good luck. This is an old Celtic tradition related to belief of wood spirits.
208