A basic rule of thumb is an E for Everyone tone; common ban reasons include intentional wrecking in multiplayer lobbies and inappropriate designs (profanity, drugs, sexual themes including 'Free Candy' etc). Repeat offenses may result in a permanent ban.
When submitting a ticket or replying to a request for additional information, do not abuse or threaten Microsoft employees or post profane, bigoted, or otherwise provocative content.
Disregard for these rules may result in the closure of your Case Review. Especially egregious violations may result in additional Xbox Live enforcement action.