If you're in the chats and PMing, remember, you have to copy/paste the section in question. if you go to a mod and just say 'so and so said this' and don't have the original chat copy/pasted they will tell you there is nothing they can do. If the Mod is on you can PM them directly, if none are on you can copy/past the conversation into a CCmail and mail it to a mod.
Things to report would be any direct attacks, sexual talk, someone seeking too much personal information, asking for money, or even asking for password.
Things that are not worth reporting are someone asking things like your weight, height, how much money you make, etc.. there is an ignore button on the PMs that you can use for questions that are just rude or obnoxious but not directly against the rules.