DON'T give a Chinese person a clock as a gift. Clocks are associated with death and funerals and a clock as a gift can be seen as a sinister action.
DON'T give sharp objects that you can cut things with as gifts, such as knives or scissors. It can actually be an offensive gift because it signifies cutting off the friendship.
DON'T give anything in sets of fours. Four is a very unlucky number in China, much like the number 13 is in many cultures. They don't have fourth floors in buildings, and "The Simpsons" was initially a flop in China because the characters all have only four fingers!
DO present your gift with two arms, and if you are given a gift, receive it with two arms.
DON'T open the gift upon receiving it unless it is insisted upon. Instead, open it later.
DON'T wrap a gift in white wrapping paper. White is definitely not a happy color in China. In fact, it symbolizes death or mourning, which is also why Chinese brides do not wear white.
DO refuse a gift several times before accepting it. If a gift is accepted right away, it can be seen as being greedy.