Objectify
I've said before that this is not a pornography site.
So here are my guidelines.
Photos that show genitals and breasts should include faces or at least heads. I don't think people should be objectified, that almost always means no face associated with the body.
In fact, that is one of the biggest differences between porn and photos. Porn seeks to objectify.
No photos of nude underage kids. There are just too many legal and ethical issues.
No photos of sex or carnal acts. Although some of the kisses and embraces come very close.
I'm straight, so most of the nudes I publish are ladies.
I do share drawings, paintings, and sculpture that show sex and orgasms in ritual or mythological context.