It contains the advice or opinions of one or more Wikipedia contributors. This page is not an encyclopedia article, nor is it one of Wikipedia's policies or guidelines, as it has not been thoroughly vetted by the community. Some essays represent widespread norms; others only represent minority viewpoints.
Open your preferences, and check the "Treat the above as wiki markup" checkbox - this allows you to fully customise your signature to your own liking.
Read and go through WP:CUSTOMSIG to get started. Take your time and have fun with it. Be sure not to use excessive markup for accessibility reasons. You can use your sandbox to test markup as well. Don't forget to save your changes.
Far easier for users to identify several posts by the same person in a thread due to a contrastofcolours. It's much easier to see who said what in a big discussion at a glance than if everyone has the same boring signature
Avoid leaving duplicate comments or accidentally closing a discussion that you !voted in
On some computers a fancy signature might not display properly, although that's becoming rarer all the time.
Signatures that use obsolete html tags like <font>...</font> clog the Special:LintErrors/obsolete-tag list, creating additional work for those doing cleanup. These signatures will not render properly if browsers drop support for font tag. See WP:SIGFONT for details.
Wikipedia is your experience, so make the most of it, however you feel is necessary! Whether it's for practical use or for personal amusement using a custom signature is a great way to leave your unique mark on the site and its many discussions.