When a kid goes to school apart from ABCD he is most importantly taught manners. How to talk to someone? How to be polite, how to eat your food properly etc. are taught to him. But as the kid grows up he tends to forget many of them as a result we find many ill-mannered adults around us. The uncles who walk around in vests but find it objectionable when a girl walks in a crop talk. If you understand this then this is not only the concept of thumb rule but also of the manners. Who told these uncles that their nudity is not objectionable?

Well apart from this have you ever seen people those who does not refrain from trying out your clothes or footwears I mean anything that is of your size. Where are has the tradition of asking before gone? Asking someone before using their things is not wrong. You don't barge into someone's house you ask for permission first. Treat their things in the same way. 

Do not peep into someone's phone. People have this annoying habit of peeping into other's phones. Don't do that. I know people are always interested in other's lives but always think that you have your own life to be interested in first. Also if someone shows you a picture on their phone then do not swipe to the next photo. That is totally unacceptable. That is one pathetic habit. Learn to respect boundaries. If you can't then reverse the situation that how will you feel if someone does the same thing to you? Don't do things that you won't accept if will be done to you. As simple as that. Character, discipline , dignity are all the important factors which can be achieved only if you start with your manners. Good manners go long way. People find using abusive language cool, but what would you say about a person who treats everyone with respect? That person will obviously be respected more. If someone takes you out for lunch or anything then do not order the expensive item, just because you are not paying. Be it with friends or with anyone. Also return the favors, or before asking for one think that how are you going to return it? Borrow money only when you are sure you will be able to return soon.