Yeah, I think the very first step for a wiki is to outline what will and what will not be on it. This gives the would-be maintainer an idea of how to start organizing content and what kind of content it will be. It will also need to answer questions such as:
* Will it need categories?
* Images: Will it need to be able to post images? Will anybody be able to post images or just select users? In which manner will images be posted/stored?
* Likewise with HTML.
* What pages should be locked? In my experience, at the very least the homepage should be, because it is _the_ single wiki page that seems to absolutely fascinate idiots into "defacing" it in various ways.
From the technical point of view, wiki engines are pretty similar nowadays, but there are some differences; in syntax, obviously, and in features they support.
I recommend that a wiki be chosen that offers at least the following features:
* User accounts.
* Selective page locking.
* If possible, allow only some users to edit certain pages.
* Page caching (you don't want every page to be dinamically generated all the time).
* Automatic generation of content indexes for every page; ie. you edit a page, you create headings, and the engine auto-generates a list of links to each section at start of page.
* Some way to organize similar pages hierarchically ie. categories in wiki-speak.
* A sane revision browsing, with user-friendly display of differences between revisions.
* Anti-spambot protection!
* A sane past revision retention policy, which ensures that nobody can erase content, or push it so far back on the revision history by malicious edits that it becomes unavailable.
* IP blocks.
I believe MediaWiki has all of the above.
There is also the issue of policy as to who can edit what. Like I said, I strongly recommend the homepage to be locked from any but select users. And I can imagine that certain pages or sections such as, say, the one for a certain mod may allow editing only from that mod's team.
Then again, by locking people away you lose the greates part of a wiki's potential (homepage doesn't count). Personally, I am put off by wikis that require login. Anonymous editing is the way to go if you want to make sure you don't lose any contribution. But it requires an editor that makes the rounds daily and reverts spam and malicious edits. If the engine makes it super-easy for him, it's a sinch and you get the best of both worlds.
This issue is quite complex. Ever since wikis appeared people debated complete freedom of edit vs locking stuff down. Some favor an extreme where it's completely open and bad stuff is simply reverted and backups used in worst case scenarios (passive resistance), whereas others will ban IP blocks and require logins at the drop of a hat.
It can get quite philosophical. Maybe
reading this can help.
Bottom line, lay down some ground rules and make some decisions first.