Rules for what is allowed being explicitly allowed (or banned) may be useful too. What some find tame others might find to be horrific and extreme + what may offend advertisers and what not.
One of the fetish sites I use has a post about content guidelines "due to obscenity laws in the US, Canada, and some European countries, if we openly fantasize about certain topics we can find ourselves in hot water.
To protect the community, we think it's best if people don't publicly eroticize any underage, incest, zoophilia, necrophilia, or scat fetishes they might have"
Blood is also not allowed.