It is good to be polite. People like you more when you are polite. Always say please and thank you. If you ask for some milk, you should say, “Please, may I have a glass of milk?”
When someone gives you the milk, you should respond with “Thank you.” It is not difficult to be polite. You should not push or shove people.
You should cover your mouth when you cough or sneeze. You should address people properly. If you are trying to get someone’s attention, you would say, “excuse me.” You wouldn’t say, “hey you.” There are table manners. That is where you eat properly and politely at the dinner table.
You don’t shove food into your mouth. You don’t reach over other people’s plates. You don’t talk with your mouth full. All of these things are common sense. Being polite is mostly thinking about how you would like to be treated. You wouldn’t want people to be impolite to you.
It is not polite to point at people. It is not polite to burp out loud. It is not polite to use someone else’s things without asking first. Being polite just comes naturally if you have been brought up in a home where everyone was polite.