Toe the line:

To do what is acceptable without causing trouble to anyone.

Good conduct:
Good conduct is determined by national laws and informal understandings that govern acceptable public conduct within a nation.
Anti-social behaviours (definition taken from Wikipedia):
Anti-social behaviours are actions that harm or lack consideration for the well-being of others. It has also been defined as any type of conduct that violates the basic rights of another person and any behaviour that is considered to be disruptive to others in society. This can be carried out in various ways, which includes but is not limited to intentional aggression, as well as covert and overt hostility. Many people also label behaviour which is deemed contrary to prevailing norms for social conduct as anti-social behaviour.
When in Rome, do as the Romans do:
When in Rome, do as the Romans do (often shortened to when in Rome) is a proverb attributed to Saint Ambrose that means that it is advisable to follow the conventions of the area in which you are residing or visiting.
Saint Monica and her son, Saint Augustine, found out that Saturday was observed as a fast day in Rome, where they planned to visit. It was not a fast day in Milan, where they lived. They consulted Saint Ambrose who said "When I am here (in Milan) I do not fast on Saturday, when in Rome I do fast on Saturday." That reply is said to have brought about the saying "When in Rome, do as the Romans do."

Golden Rule:
  • What you wish done to yourself, do to others.