The rules are pretty simple and few:
1) Always give credit where it's due. Plagiarism isn't cool. If you're linking to someone else's fic or Tumblr post, make sure you tell us. (That's just proper, ya know?)
2) No bashing is allowed. Yes, people are stupid, but keep it outside the forum. This is a place of Satyr (or Sansyr ) loveliness.
3) Sophie Turner is a minor in the US and probably a lot of other countries, so keep that in mind when you post things about her. Sophie and Sansa are different. Sansa is a woman grown. Be especially mindful if you express shippyness over Sophie with Aidan (which I totally ship them as friends, but I think he has a wife and Sophie's young, etc.)
That's really all I can think of. I don't care if you cuss like a sailor (I know I do) and kinky fics are encouraged. We're all mature people here. (And if you are a minor, none of us are responsible for you. You WILL see/read 18+ stuff here, likely.)