Links
How to Link
HTML
Use the Link button
Make it obvious where the link leads
Contrast
Encourage flight?
Sidebar
What to Link
External links
Related content
What is the reward for following the link?
Internal links
What not to Link
Punctuation marks
Headlines
Why to Link
Credibility
Site traffic
Interactivity
1) Provide context for your article 2) Provide attribution 3) Reward readers with something extra or another layer or dimension to the story
References
http://webdesign.about.com/od/beginningtutorials/qt/external-links.htm