The biggest cause for arguments in a roleplaying game is that one person tries to be the center of attention, and it pisses everyone else off.
People can quit, games can be abandoned, flame wars erupt – with swearing and harsh words thrown at each other, all because someone tried to make their character more awesome than someone else.
If you’ve not heard of this phenomenom before, look up “Godmodding” which can mean many things, but basically it’s a character that’s way more awesome than they should be (there’s an article about that here). Another word for it is a “omnicompetent character”.
I know it’s tempting to write a character who’s’ totally AWEZOOM!!1, but having flaws is a good thing too. It grounds the character, and makes them more interesting, and realistic. Read this article about creating a flawed character.
Remember that this game isn’t about your character. It’s about all the characters, equally. Think of your game as a TV show with an ensemble cast. There’s no 1 main character or hero. All characters are heroes, equally, so make sure your character fits in and doesn’t take the limelight away from the other characters. Or those character’s players might get pissed off.
Top photo by Andrew B. Myers