1. Opinions stated like secrets (e.g. "I think Sam is a stronger character. I'm afraid to say anything because fandom will eat me.") will be posted. But opinions stated like fact (e.g. "DEAN SUCKS. SAM > EVERYBODY!") will not. We get that you think so. Okay. But why is that a secret?
2. Random stuff on fandom images ("I love you" with a Supernatural background) will not be posted. Secret on fandom image != fandomsecret. Make it clear how it's related to some sort of fandom or something related to a fandom (you met through fandom, et cetera) unless the image does so.
3. Personal attacks. Secrets without names blurred (or something along those lines) that bash a specific person. Flame a fic, fanart, character, or fandom all you like, but when it gets to specific people, they won't be posted at all.