You don’t know people.
So stop assuming that you do.
What you know about others is just a fraction of who they are. They wouldn’t let someone like you know everything about them. They aren’t like you, letting the whole world know about their lives, every moment of it.
You need to learn to respect their privacy, to know that people release bits and pieces of themselves slowly to you as they start to trust you. Never assume that what you know is their whole story. Don’t finish off their sentences, don’t cut into their sentences, don’t interject, interrupt, intrude and never ever talk more about yourself than about the person you’re talking to.
Show respect, have fun when the time is right, but always guard your manners and the art of engagement.
I know, sometimes you slip up, forget something, make a mistake but know this, apologise and move on. We’re humans, we fail sometimes and it is up to us to pick ourselves back up and start stronger.
Be conscious of your actions and your interactions with other people. Be humble, know that people love to talk about themselves and you should let them, maybe, through that you’d know more about them.