It's commonly known that the Chinese invented chopsticks (or kuaizi in Chinese, Hashi in Japanese) as a set of instruments to be used when eating but the reason behind that is not commonly known. Actually, the Chinese were taught to use chopsticks long before spoons and forks were invented in Europe (the knife is older, not as an instrument for dining but as weapon). Chopsticks were strongly advocated by the great Chinese philosopher Confucius (551-479BC). Chinese people, under the cultivation of Confucianism, consider the knife and fork bearing sort of violence, like cold weapons. However, chopsticks reflect gentleness and benevolence, the main moral teaching of Confucianism. Therefore, instruments used for killing must be banned from the dining table, and that is why Chinese/Japanese food is always chopped into bite size before it reaches the table.
There are superstitions associated with chopsticks too. If you find an uneven pair at your table setting, it means you are going to miss a boat, plane or train. Dropping chopsticks will inevitably bring bad luck. Crossed chopsticks are, however, permissible in a dim sum restaurant. The waiter will cross them to show that your bill has been settled, or you can do the same to show the waiter that you have finished and are ready to pay the bill.

General bad practice to avoid:
* DO NOT use your chopsticks to shift dishes around.
* DO NOT wave your chopsticks about in the air while trying to decide what to eat next or as gesture during talking.
* DO NOT rummage about in the food looking for the tastiest morsel.
* DO NOT pick up a dish with the hand that is holding the chopsticks.
* DO NOT point your chopsticks at people when you are eating; never lick them or spear food with the points
* DO NOT hold the chopsticks with your fist, since this appears as if they are being held as a weapon.
* DO NOT pass food from your chopsticks to another person's chopsticks. place the food down on a plate to transfer.
* In situations where you are taking from a common food dish or if you are serving someone, serve using the opposite end of the chopsticks. (the end which doesn't touch your mouth.)