SubmissionGuidelines

Add Your Name: when editing a page, there's an edit box on the right pane, in the "Change Attribution" section. Please put your nickname or your email address there. This is how we know who changed what on each page.
Create A User Profile: create a Wiki topic on your name (for example, if you name is John Doe, you can create a topic called John Doe). This will create a page where you can put some contact info we can use if we ever need to get in touch with you (questions about your contributions, etc.).
Properties: a WikiPageProperty is a useful thing for indexing and maintaining GURPS Wiki contents. Get to know the Summary, Authors and Keywords properties. Try to update them when necessary, and add them to any new topic you create. Also, use the Note and ToDo properties whenever you have a remark, or whenever there's some unfinished business somewhere. This way, they will show up on the Contributors Page. If you want, there's a list of Wiki Properties Used In GURPS Wiki you can use as a reference.
When In Doubt, Use The PlayPage: the Play Page is your friend!
Give your sources: if you're basing your contribution on internet material, please give the links. A common practice is to summarize and present Steve Jackson Games Forums threads about GURPS in a comprehensive and useful way. In this case, if applicable, insert a link to those threads in your contribution.