The lost art of a firm handshake and eye contact
Been teaching my boys proper etiquette since they were little. You look a man in the eye when you shake his hand. You stand up straight. You speak clearly. It takes two seconds and people notice. At my youngest's school event yesterday a teacher actually commented on his maturity and confidence. That comes from knowing how to conduct yourself with dignity. We're losing this stuff and it bothers me.
This is huge. Simple stuff but it sticks with them. My oldest now introduces himself that way without being told, and I catch myself smiling every time.