To show the respect to the elders, do not call their names directly. Add a Mr. or Mrs. or other title.
Do not embrace or kiss when greeting or saying goodbye. Handshake is OK.
Do not point the bottoms of your feet to any person.
Do not stick your chopsticks up right in the rice bowl.
Do not open a present in front of the giver.
Do take your shoes off when entering a Chinese home.
Do insist several times for giving a present, and with both hands.
Do not write cards or letters with red ink or ball pen.