Never sign an article. This rule is pretty straightforward; signing your name on an article would indicate that you owned it. After all, this is a wiki, and everything released here (excluding things already protected by copyright laws) is under the fair use rationale.
While some fan sites may list contributors of information to give credit, we can't do that in articles. With this site being a wiki, a single page may have had hundreds of different players contributed. On the history of each page (accessible through the "history" tab at the top of the page), every contributor is listed automatically, making listing contributors unneeded, also.
In all honesty, you shouldn't sign any page except: