24) Disrespecting Boundaries. Everyone has different subjects that make them uncomfortable. Some people wince at the most benign curse word; others will do anything up to an including NC-17 roleplay, but have a particular kink they find disturbing. It's inevitable that at some point in time, your or another will accidentally trespass through someone's boundaries and make them uncomfortable. If that happens, absolutely respect the feelings of the person who is uncomfortable. Don't try to pressure them into playing something they don't want to play. If you want to roleplay subjects getting into very violent or sexual territory, talk about what is an is not acceptable in advance.
25) Spotlight Hogging. In roleplay, it is hard for too much attention to be focused on multiple characters at the same time. Instead, only a few characters get to be in the spotlight at a time. Spotlight hogging involves always trying to take scenes or roleplays in a direction that will result in your character getting attention. When Character A is making a tearful confession to the group about how she betrayed them but she is sorry, that isn't the time for your character to suddenly pass out from their their dangerous illness or reveal his angst filled past. If roleplaying with a partner, don't always push for plots surrounding your character while rejecting and and all ideas that give the attention to someone else. In short, be fair.