(→What can I have on my user page?: red link removal, Replaced: public domain → பொது உரிமைப் பரப்பு, using AWB)
You might want to add quotes that you like, or a picture, or some of your favorite Wikipedia articles or images, or something like that. Also, someone may choose to award you a [[:image:barnstar.png|barnstar]]. In the unlikely event that your editing privileges on Wikipedia are revoked, a notice of this may be placed on your user page.
If you want to [[m:Guide to the CC dual-license|dual-license]] your contributions under an additional license or declare them all [[
In general, avoid substantially editing another's user page without their permission, but feel free to correct typos and other mistakes. Some users are fine with their user pages being edited, and may even have a note to that effect. Other users may object and ask you not to edit their user pages, and it is probably sensible to respect their requests. The best option is to draw their attention to the matter on their talk page and let them edit their user page themselves if they agree on a need to do so.