What are some unwritten hockey rules?

Hello, tomorrow is my first time playing in an actual league (U15 HL) and I’m really nervous. Are there any unwritten rules I should know so I don’t mess anything up? (Like locker/change room rules and stuff.) Also, the evaluation is pure scrimmage, are there any good tips to give me? I kinda still don’t understand the position during faceoffs at the 4 dots. (I’ll probably be playing D) thanks.