Link words in the article to other articles. For example, link jargon and technical terms to articles that explain them. Link words that lead to related articles, especially about organizations, people, and places. Link common words used in a technical or uncommon way. But don’t overlink, as discussed in the box on How to Create Internal Links.

When you add links, check to make sure they don’t end up at disambiguation pages (???). While someone will eventually fix them, they defeat most of the purpose of linking in the first place. (You can also link to just a single section of an article, as described on Incoming Links to Article Sections.)

Red links are an opportunity, not a problem. If you think there should be an article about something, but there isn’t, create the wikilink anyway. If the wikilink turns red, showing that such an article doesn’t exist, then check the spelling (a Google search is good) and recheck the capitalization (except for the very first letter, it matters in Wikipedia page names).

If you find there’s a relevant article in Wikipedia but under a different name, click the red link so you can create a redirect (Adding a Redirect), and then change the wikilink in your article so it points directly to the new article.

Check incoming links. You find these by going to the toolbox at the left side of the screen, and clicking the “What links here” link. Treat this list as possible outgoing wikilinks to add to your article, although you’re not required to do so. These articles are also places to check for good sources that you might use in the article you’re working on.

Consider linking to this article by editing other articles. If the article you’re working on has an outgoing wikilink to another article, and that other article doesn’t link back (as shown in the list of incoming links), then perhaps it should. You may be able to expand that other article slightly, with a sentence or so, and an additional wikilink. (You can link the article to WikiProjects by editing the article talk page; see the box below.)

Add categories. Categories tie articles together in a way that readers find useful. See page 324 for details.

Create or add to the “See also” section. Per the guideline Wikipedia:Layout (shortcut: WP:GTL), the “See also” section “provides an additional list of internal links to other articles in Wikipedia that are related to this one as a navigational aid.” The “See also” section shouldn’t duplicate links already in the article. It’s for linking to subjects closely related to the article.