The only rule that you need to remember in China is that there are no rules.
Chinese societies is made of many things and Western logic is not one of those things. As I recently read in one of my business books, Chinese society is shame based and American society is guilt based. Consequently, Chinese will not feel guilty for doing the wrong thing or even give it a second thought unless the action is actually brought to attention (i.e. they are caught). Knowing this will save anyone endless grief when living in China. One should not be mad that there is one person riding their bike in the wrong direction and there are 100 scooters and bikes headed straight at them. In the United states we might say that they are dumb and not following the rules of the road. In China, however, they might say, "it was more convenient for that person to be on the wrong side of the road!"
Lesson to be learned: The only rule is there are no rules in China!