Always stand up to shake someone’s hand. (NEVER shake a person’s hand while sitting.)
Always get up out of your seat to greet a guest and walk them to the door when they leave.
Grandpa was a Marine, though you’d never know it. Slight in build and oh-so gentle natured. But underneath he had a good bit of grit. He never complained. He once told me “You can stand any amount of pain for a little while.” (Basically saying suck it up and hang in there until help arrives.) I’ve never forgotten it.
Adult whining is worse than kid whining! We all have unpleasant comments to say in every day life, but do your best to keep snarky comments to yourself. Be mindful of what you're putting out there.
Practice people skills: Firm handshake, introducing yourself, being courteous when encountering / being on receiving end of someone’s rude behavior, offering your seat (never sit while someone with gray hair, pregnant belly, any sort of injury or really anyone who is older or who works harder is standing.)
You can get into big trouble (with school and the law) even by fake / joke threats of violence (bomb threat, etc.)
No jokes or pranks that have anything to do with violence.
You were THREE years old when you caught sight of a half-dressed beautiful woman. You didn’t have much of a vocabulary yet but when your eyes got wide and you said “BAM BAM” I knew exactly what you meant. (Woman was Jessica Biel in an Adam Sandler movie.)
Make yourself a good hand. Don't wait to be asked, just jump in when you see a need. Wash a dish, make a bed, change a tire, help out a friend or a stranger whenever you can.
People want to be heard. Listen to your clients, even when they're upset. Don't make excuses or anything, just let them talk. They mostly just want to be heard. Once they're calm, you can solve the problem.
You may end up being a big shot, Good for you! But check yourself. The good lord wasn't above washing his friends' dirty feet so please don't feel like you're above any task that needs to be done. Enjoy your success but stay humble.