Use common sense.
No begging, no spamming, no swearing, no spoiling, no advertising without permission. Also, don't forget that advertising your items and listings is permitted only in the Trading chat.
You should also refrain from posting links and keep the chat civil. Being very vulgar or offensive will not be tolerated.
Remember. You can use "ignore" feature to mute other users, should you find them annoying.
To do that, click on the red gear button, which appears when you hover your mouse cursor over the nickname in chat.
You can also report an user and exact message you're reporting him for. Our moderators will review it and react accordingly.
Additionally, please check if you're in the correct chat room and that you're using the language appropriate for the room you're using.