Copying myself here - rules of D&D etiquette from a player's perspective
Assert your dominance by attacking the first character you meet.
If you roll a natural 1, ignore it and reroll it until you get a high number. Say the other rolls were practice rolls.
Talk about Naruto. Especially if you have no idea what a naruto is. Make things up. Yell at anyone who corrects you.
If you die or take damage, flip the table over, scream, and lock yourself in the bathroom. Refuse to come out until your character gets a bag of holding and an apparatus of Kwalish. When you come out, announce the apparatus of Kwalish is useless and you want to sell it so you can buy a holy avenger.
Roll up characters when it is not your turn. Have the secondary characters join the party as your loyal minions. Attack any player who talks back to you.
Make fun of other players who have backstories for their characters.
Write a ten page backstory for your character. Make sure it involves time travel and Star Trek. Pro players always do this.
Buy cattle, pet dogs, cats and other animals. Use them to detect traps. Use whatever healing magic you have on them before any other player characters.
Other players will respect you more if you show up in character, especially if you're playing a deaf mute monk with alcohol fetal syndrome and anger issues. They will be impressed by your acting ability.
Speaking of booze, be sure to bring some and drink when your character is in a tavern. Roleplay your attempts to start a bar fight with physical demonstrations.
Carry a real sword to the game.
Use the real sword to execute dice that fail you by rolling poorly.
Don't let the police get in the way of real roleplaying.
Make sure your character has the alchemy skill. Invent gunpowder.
Set up sweatshops filled with whatever goblins or orcs you capture and invent the assembly line.
To show how good your character is, adopt some orphans and have them become your apprentices or squires. Children provide half cover.
Offer to join whatever evil army or cult you are tasked to defeat. Demonstrate your commitment to evil by killing your apprentices or squires.