How to be a good chinese daughter in law?

The first thing is to be sure of the person you intend to marry, that being because of the massive number of people trafficking for forced prostitution scams.
PM me and I'll be more than happy to assist if that is a possible concern.

Other than that clear and present danger, you must learn as much as possible of the culture and master the language/languages as quickly as possible

When you get married, your in-laws will move in with you. They will start taking over the household. This will be handy when you have a child as a great burden in raising the child will be lifted off your shoulders. You should make sure that you are on good terms with your husbands mother, or else there will be friction that will not be easy to take.

You will be expected to have a first son. There will be disappointement in your husbands parents if this is not the case, and they will blame you for not giving birth to a girl. If you want pets, you will need to ok it with the mother. All furniture arrangments and meals will be her pervue. Therefore, it is critically important that you discuss all this with your future husband before you get married.