Draft guidelines for students.
Be polite and show respect to other members of your group. Give praise for good contributions and make your comments constructive. But…
Don't take it personally when people comment on or edit your work.
Dive in, add text and edit other people's work. It's how wikis are designed to work. If you make a mistake you can always revert to an earlier version. But…
Avoid radically altering other people's work, especially if you don't agree with them. Seek out a way to reach agreement by talking to them about it directly if you can, or by using comments or the discussion forum.
Structure the information on the wiki by using section headings, lists, and by breaking it into sub-pages where appropriate. Review the wiki regularly to make sure it's tidy and the structure's still appropriate to your content.
Reference your work and give full credit to sources, as you would in any other assignment.