You might want to do a QuickSanityCheck to ensure that the “wiki-way” really is the right path for you, your people and/or your project. You should take time to read A Group Is Its Own Worst Enemy by Clay Shirky.
Once you are sure that you want/need a wiki you’ll have to pick the right wiki service to use, or the wiki engine to install. A list of wiki software is available at Wikipedia, hosted options are listed at Wikibooks and the hive-wiki connects the center-wikis of wiki-hives. Some of these options can be found via the Wiki Choice Wizard at Wiki Matrix. Examples of wiki using different wiki engines can be found at WikiIndex.
If you are planning to launch a public wiki (one that the whole world can contrubute to) you ought to think about how the laws of your country apply to wikis. In general you make sure you:
You should know that founding a wiki requires a lot of energy. See CW:WikiFounding for more information.
In any case, the most important part of our WelcomeFounder message applies to you as well: Congratulations!!
Founding a community is a very rewarding experience. Welcome to the Wiki World! :)