Summarize this article in one sentence.
Posh people have good manners and know the boundaries in human relations. Always say "please" and "thank you" when the situation calls for it. Say "excuse me," greet people politely, and display good table manners—such as chewing with your mouth closed. Also do not use your phone at the table or when talking to someone. Although posh people are often wealthy or "high class," this does not mean they are arrogant. It’s important to be confident in yourself and your abilities, but do not think that you are better than anyone else. Treating everyone you meet as your equal is very posh. Always show up and do your best at anything you commit to. For example, if you say you will throw a party for someone, do it and do it to your best ability. Or, if you make a mess while you’re a guest at someone’s home, make sure to clean up after yourself. Posh people have a large vocabulary and know when to employ it. However, posh people never force words into sentences that don't belong. Read and study to expand your vocabulary, but don’t use your knowledge to show off. Speak clearly and confidently. This person could be a friend, historical figure, or even a celebrity. Don't copy them precisely but do allow their way of being, their style, and attitudes have some influence on yours. That way, you can build a strong foundation on which to become a posh person in your own right. Some examples of posh people are Emma Watson, Kate Middleton, Benedict Cumberbatch,  and Eddie Redmayne. A posh accent is often associated with the English aristocracy, as well with educational institutions, like Oxford. This accent is referred to as posh, but is actually called Upper Received Pronunciation English (Upper RP). Essentially, to sound this way, practice an English accent. Then, pronounce your consonants more fully. Also, pronounce vowels æ sound leaning more towards the “e” sound.  For example, when saying “man,” it will sound more like “men” in a posh accent. Also, a weak “I” sound will sound more like an “e.” For example, “quickly” should be pronounced more like “queckly.”
Display good manners. Avoid an arrogant attitude. Take responsibility for your actions and obligations. Be articulate. Look for posh people you admire. Practice a  posh accent.