Optimize your writing for users with impaired vision
Users with screen reader devices will scan and skim your web page in a manner somewhat similar to the way a visual user will. Screen readers can be programmed to read only headings, subheadings and links. When something of interest pops out from this "skimming" process, the user can stop and have all the information in a particular section of the page read completely.
The first step is to write meaningful headings and subheadings that contain important words and phrases. The first paragraph under each heading should clarify what the section of the page content is about.
Next, make sure that link text is informative. Link text should give users some idea what they will find when they click. Link text like "here" or "click here" is not informative. The link text in this example is descriptive and informative: Google is trying a similar thing with HTML5 Rocks. It's obvious that a click will take the user to HTML5 Rocks.
Finally, write alt text that gives an alternative description of the content or function of an image. For example, in book reviews such as my recent one of Mobile Design and Development, the alt text for the image of the book cover is "get Mobile Design and Development at Amazon." While it does not say that the image is a book cover, it does tell the user what happens if the image is clicked–functional alt text.