It usually goes without saying that to upstage your canon is bad form, and so I will skip the explicit restrictions on spiritbending and animalbending and playing the other Avatar. What’s more important is that, in your inevitable-yet-paranoid avoidance of Mary Sue-dom, you don’t forget that your character is allowed and indeed encouraged to be active, relevant and unique. You have permission to be interesting.
Prepare to be Jossed
The nature of the game is such that things you establish always run the risk of being overwritten by canon. Even those who “play it safe” will never be risk-free. Accept that you may need to perform triage on your ideas or occasionally discard them completely – your community will mourn the loss with you.
Let Korra be your guide
As much as possible, we'd like to keep true to the tone of the world. Everything in the game should be plausible within the confines of what we know.
Content also shouldn't be too much racier or darker than what we get from the show, even if it is more sophisticated or complex (put bluntly: no gore or porn).
Play nice with the other children
This game is chiefly a collaborative environment. The ever-changing nature of the setting makes it all the more important that we as players are willing to create and repair with one another. It’s imperative that you be willing and able to give and receive suggestion and critique.
The majority of the game is played-by-post in the public community, where characters are presumed to be face to face. Writing style should be narrative standard (quotation marks for dialogue rather than encapsulated emotes) but if all parties involved in the thread agree to a different system beforehand, that's perfectly fine. There is no minimum word requirement.
Your character’s journal is for use at your own discretion, mostly. You can use it mostly for OOC housekeeping, you can use it for crack and AU, you can use it like an IC bulletin board, you can use it under the pretext that exchanges made within are conducted by carrier pigeon. Should we find telephone technology in the age of Korra, that will probably be the chief function of journal posts.