Every page and sub page should be identified and categorized according to how you'd want it if you were. Having built your site map you're ready to build your navigation. Navigation is the second most important key to keeping visitors on your site and not clicking away. It has to do with comfort. As long as they can find what's on your site, providing it is interesting, they'll stay.
Uncomfortable surfers click away to sites that are comfortable.
Its easy to avoid those mistakes. Start with the main pages - the most important ones. If so, link to every page from your main page, and, consider linking to every page from every page as well. If so, your job is a little more difficult. Fortunately, you have the opportunity to give the visitor subtle clues about your content and where it resides.