To build a great Web site, you must define its objectives. Only then can you define and prioritize the usability aspects of your site to meet your intended users' needs.
Let's take a few this site's objectives and usability solutions as an example:
Site Objective
95% of Web pages must theoretically download in two seconds or under on a 56kbps modem.
Usability Solution
To minimize the download time of each Web page, we minimized the number of words and graphic files on each page.
Site Objective
Content must be understandable by a seventh grader. Since we appeal to an international audience, whose first language may not be English, this is crucial.
Usability Solution
All text on this site has been checked for readability.
Site Objective
User must be able to find the specific content they are looking for in three clicks or less.
Usability Solution
There is a search form at the top of virtually every page for quick and easy access.
Think about defining similar objectives for your site. Don't forget that the most popular features of your site should be positioned prominently on the home page, so that users don't waste time hunting for them.