Foreigners are not expected to know all of these things the minute they step off the plane and will be given great latitude, however your knowledge of what is not acceptable can make your transition to life in China much smoother.

If you want someone to come to you, don’t wave them over with an upturned finger. This is impolite. Wave them over with your fingers turned down, as if they were sweeping something toward you. The same motion is used when hailing a cab.

When using a toothpick in public, cover your mouth with your hand.

When eating with a group, if there is a dish everyone is sharing (which is customary), do not use your chopsticks or the spoon you are eating with to dish your food. Use the serving spoon to dish into your bowl or plate and then use your spoon or chopsticks to eat.

If someone gives you a present, it’s best not to open it in front of them.

When someone gives a business card to you, do not stick it in your hip pocket. Also, don’t stick it in your wallet and then put your wallet in your hip pocket. You would be symbolically stating that you want to sit on them! Putting a business card in your wallet and them placing the wallet in a front pocket is no problem.

After eating a meal, never leave your chopsticks sticking up in the left-over rice at the bottom of your bowl. This is what people do at shrines when offering a meal to their ancestors' ghosts. Doing it in a restaurant would be a terrible curse on the proprietor.
Sometimes funerals, weddings, or religious ceremonies will suddenly occupy a whole street without warning. Even though they’re blocking your way, it's not good to walk through such a gathering.

When you're just getting to know someone, and it begins to rain but they don't have an umbrella, it’s bad luck to give them an umbrella to go home with – a sure omen that you’ll never see each other again.( the Chinese word for umbrella-san-sounds like the word for “to break apart”.) This is particularly important for dating couples the first few times they go out together. If you like our new friend, take the time to escort him or her with the umbrella out to the bus stop or taxi.

The following gifts and/or colors are associated with death and should not be given:

Clocks (giving a watch is okay)
Straw sandals
A stork or crane
Handkerchiefs
Anything white, blue or black

Likewise, its best not to give a handkerchief as a present. Given that this is something that is used to wipe away tears, a gift of this nature is perceived to actually bring them some kind of bad fortune, IE) the cause for crying.
Believe it or not, finishing everything on your plate is NOT a good thing in China. If you eat all of your meal, the Chinese will assume you did not receive enough food and are still hungry.

Don't lose your temper. You can be form as long as you remain polite but to lose one's temper is an absolute loss of face.
You can give away your used stuff but not as a gift, no matter how nice it is. But don’t worry, if you accidentally give an unlucky gift, the course can be set straight if the receiver gives you a coin as a token payment – then it technically becomes a purchase instead of a present.

Remember when entering any home in China that you need to always take off your shoes.

When sitting, do not point the bottoms of your feet to any person. Try to sit cross-legged or tuck your legs underneath you.