document updated 12 years ago, on Sep 6, 2011

The two biggest things you can do to reduce ads when viewing Wikia websites is:

Log in. That's it. You can do this totally anonymously — wikis that you visit won't have records of you, unless you make edits. Just logging in reduces the number of ads. (the "Show all advertisements" preference will reverse this change, while logged in, so that administrators can see the website exactly as visitors do)
Change your layout to Monobook. The setting is in My Preferences > User Profile (the first tab) > Site Layouts. This completely removes all ads.
- Unfortunately, this is a setting that has to be done for each individual Wikia wiki that you visit. There's no way to make this setting apply to all Wikia wikis at once.