With its own link at the top of every page, your user page is as accessible as Wikipedia's Main Page. Because of this, it is your customizable Wikipedia navigation hub. Just place your favorite Wikipedia and external reference links on your user page, and you can access them instantly anytime you want from anywhere on Wikipedia.
For more ideas on how to customize your user page, see Wikipedia's User Page Design Center. There's also a help department there too.
Internal links are a great way to alert users to pertinent information. However, remember that excessive linking can detract from an article. Only create links that are relevant to the context of the article. Internal links are created by placing double brackets around the word you wish to link, for example: [[Subject X]]. You can link to a specific section by adding the # sign and the name of the section after the article name. For example: [[Subject X#The beginning]].