They're simple in approach, but there's much more in behind the elementary idea.
1. Collect data about users and feed them what they want. While no one wants a feedback loop, there is a lot of sense in reinforcing what's been successful.
2. Link within stories to your own related content. In other words, keep people inside your site or network.
3. Link to relevant content at the end of a post. Don't let people leave empty-handed.
4. Improve headlines. This is an acute issue for search engine optimization.
5. Use search terms to locate additional, relevant content.