Without Thinking
A lot of us talk and move before any thought catches up. Add emotion to the mix and it gets worse. You blurt something out, then scramble to apologize. Or you don't apologize at all.
Try watching first. What are the people around you actually doing, feeling, thinking? Take that in, and only then decide how to answer, if answering is even called for. And check your own state while you're at it. Three hours stuck in traffic will leave anyone short on patience, and whoever you meet when you finally arrive tends to catch the overflow.
Emergencies are their own category. You move fast because you have to, and sometimes that's right. But once the dust settles you may realize you read the moment wrong and did something you never would have done if you'd understood there was no emergency in the first place.
Some mistakes come from good intentions. You meant well, you acted on it, and later you can own that it was the wrong call. If you'd known the full picture, you'd have chosen differently.
I've watched people step in to correct someone else's behavior, convinced they're being both righteous and spontaneous, when really they're seeing only the slice of the situation that confirms what they already believe. There is almost always another piece of the story, something that would explain the other person's behavior, that the corrector has no idea about.
One more thing: don't let gossip you've picked up color how you treat someone in an ordinary moment, even if that person has genuinely done something wrong somewhere else. When they're not doing anything to you right now, and you're not involved in whatever they did, does any of it give you license to be rude? Nobody asked you to be judge and jury.