A costly mistake a new entrant of China can make is not registering in time at the local police station.
Sometime in the recent few years the requirement to register your residence at the local police station has been tightened from within 10 days to within 24 hours of your arrival in China. It doesn’t matter if you are residing at the same place as you always have, you still need to register.
You will need your passport, details of your legal work status and details of your rental agreement and landlord. For most people, this will involve taking the office worker responsible for foreigner affairs along with you to handle the translation and all the details that even an experienced expat would be hard-pressed to fully understand.
Missing the required time period upon entry into China exposes you to increasing fines and/or treatment as a criminal, with a long interview, fingerprinting, blood testing and other treatment verging on humiliation. The local police are also likely to have a less refined understanding of international standard behavior. While an office manager worth their wage should be able to deal with local police in short order, it can be a horrible and stressful event that you are better off avoiding.
Believe me when I tell you.