At first, I completely failed at creating a wiki, then having a strong community. It took about 5-10 tries for me to actually get a good and strong community. Here are a couple tips for getting your wiki to grow:
1. Get new features from Wikia. (ex. Wikia Labs Top 10 Lists) It keeps your wiki interesting and interactive.
2. Don't protect tons of pages. It makes a user feel unwelcome to the site.
3. This one is obvious: Be friendly to your users.
4. Spread the word on other wikis via blog post. If you get a user from a very high traffic wiki, (ex. Glee Wiki) ask them if they could throw around the word of your wiki.
5. This tip is only on some wikis (if you don't have them send a request through Special:Contact). Get badges. This encourages users to edit your site.
6. Create a wiki newsletter. This keeps users in touch with what's happening on the wiki. If you want a subscription page, name it NEWSLETTER NAME/Subscribers.
Well, that's all I have for today. See you all later!