Remember, three important ideas shape good manners--custom, common sense, and consideration.
Custom is the habit of doing things a certain way. For example, in Western culture, most adults greet one another by shaking hands.
Common sense is what makes sense to most people. Ask your child, is it polite to push your way up an escalator just because you want to get to the top faster?
Consideration is thinking about the way the other person feels. Being rude to someone is bad manners--not because a book says so, but because it hurts that person's feelings.