Shake hands before playing chess to show respect for your opponent.
Don't make actions and sounds that affect your opponent's thinking, such as making faces, singing and humming. Some people love to gossip, and this kind of incident is very annoying. Usually the referee can only remind you, not foul. )
After playing chess, don't laugh at your opponent's level, try to meet his simple chess-dividing requirements.
When admitting mistakes, turn off the clock and shake hands.
In chess, don't consult others or software (this is a foul, you can report it, but it is difficult to verify it in the primary game)
In fact, you can see that in professional competitions, many people start to watch other people's moves after taking a few steps. Although this is not a foul, it does not respect their opponents. Chess is not an aristocratic sport, and there is not so much etiquette, as long as you are "normal".