One of the greatest powers of the Internet is the ability to cross-link related documents, allowing the reader to explore and learn in non-linear fashion. Content authors must remember, however, to clearly indicate the destination of hyperlinks, both for internal navigation, but also (and perhaps more importantly) for external links. Clearly indicating the destination of a link allows all users to decide if they wish to pursue the link now, in the future, or not at all. It also aids readers who choose to print out individual web pages for later use.
Links should avoid vague link text such as "Click Here" or "Read More." Site visitors should be able to understand the result of activating the link, even if they are not reading the link-words in context.
Try to avoid language that requires spatial or visual references. Keep in mind that not all users will experience web pages in the same way(s) you may be envisioning. For example, instructing readers to click on a link "on the right" does not take into consideration the fact that visually impaired users do not "see" left or right. The same holds true for references to colors or shapes (i.e. "click on the round button," or "click on the green text").
Links to internal web pages should include the name (title) of the linked document as part of the screen text. Links to other documents within your website should provide, as part of the linked text, the title of the referred page. This allows readers to determine whether or not they wish to follow the link.
Links should be clearly differentiated from body text. Unstyled HTML text will place a line under linked text to indicate to the end user that there is a link available. While Cascading Style sheets allow us greater sophistication in the visual rendering of screen content, it is highly recommended to continue to underline link text in some fashion, as studies show this is still the most expected display of links within a web document.
Finally, site visitors should be able to navigate to and activate all links on the page via the keyboard.
Read through the links on the page, imagining yourself as a first-time site visitor. Is the purpose of each link clear? Can you tab to all links? Are all of them clearly distinguishable, whether you hover over them with the mouse or reach them with the keyboard?