What table manners should you actually follow?

I took a lot of etiquite courses growing up, but I’ve noticed that not all of the rules are followed, and might just be outdated. What are some (USA) table manner that everyone should follow? Also, to change things up, anyone have any horror stories?

My short list is: always chew with your mouth closed. Make as little noise as possible. Finish your food at the same time as others. Eat slowly. Put your silverware at 4:20 when you finish. No talking with food in your mouth. Don’t pick at your teeth. Sit up straight.

Do we really need anything else? Can’t wait to hear the horror stories!