1) watch your wallet: lots of pickpockets in crowded places
2) Only drink bottled water
3) don't eat in restaurants that look small and dingy, often they cook with spoiled vegetables and meats. NEVER eat anything cooked on the street.
4) no need to tip!
5) don't ask beijingians or shanghaians for directions, they will almost always give you directions going in the opposite direction. My advice is: ask at least 6 people, and if two or three of the directions given are the same, then they are probably true.
6) when buying things from sellers who allow haggling, always make sure the product your buying is REAL. that includes computer hardware, cigarettes, food products, even bottled water!
7) when taking a taxi, discuss pricing FIRST! otherwise the taxi driver will take you on a tour that will cost you plenty
8) don't trust ANYONE!!!