As most of you know about China culture Leftover food is bad, Chinese people will eat their own meals until there's nothing left because that causes bad luck. So you should eat it all.
In china, when you drink. You should hold your glasses lower than are older than you to show respect.
Other important things. You shouldn't write with red pen because that shows disrespect or it means protest., don't use clock or books as the gifts to someone because in Chinese Clock pronounced the same as funeral and the word book pronounced the same as fail. So you should be aware of those things as I said when you want to visit China.