(I know countless other users have already done blogs like this, but I'm going to do my own version anyway.)
Staying safe online is getting increasingly difficult these days, especially for young and/or inexperienced users. Wikia may seem like a safe haven at first, but all websites have risks. I cannot guarantee that nothing bad will happen if you follow these bits of advice, but doing so can and probably will greatly reduce your chances of being cyberbullied, stalked, etc.
1. Be Aware of What You Reveal
Everything on Wikia is logged or cached, whether you know/like it or not. That message you posted in the main part of CCC? One of sactage's bots is logging it. That edit you made to a wiki page? It will stay in the revision history until the end of Wikia's run. That message you posted on a friend's wall? It can still be viewed by others even if you remove it.
If you don't want something to be forever out there, don't say it at all. Keep it to yourself, write it in a journal...but don't say it online.
In that event, block their PMs. Tell someone if they're bringing the violation(s) into the main namespaces, too. But do not answer their question if they're asking for personal info. And make sure you never make their mistake yourself, otherwise you're to blame then!
3. Don't Be Lazy With User Rights
This one is directed at people who have just acquired their first local bureaucratic position, either through adoption or trust. Don't just give anyone user rights. In the wrong hands, user rights—bureaucrat rights especially—can be used to kill a wiki from the inside out. Only promote users you trust, and make it gradual as opposed to all-at-once.
4. "If It Ain't Safe, Don't Add It"personal codes in their preferences. If you are presented with a code bit and you have no idea what it does, do not add it to your files unless a) the user is highly trusted by both you and others or b) another trusted user can explain its function.
Basically, don't add code unless you know exactly what it will do.
That's all for now! ^.^ And if you think I missed something, be sure to tell me in the comments below.