You want your users to quickly and easily navigate your site to find the content they are looking for. You also want search engines to easily crawl your site and understand the content that you consider important.
Its important to create a clear and logical structure using a navigation bar.

All sites have a home or “root” page. It’s usually the most visited page on a site and the starting place of navigation for visitors. From the home page, help visitors will find other pages on your site by creating a navigation bar. A good navigation bar calls out important sections of your site, is clear about where it’ll take visitors, and follows a logical structure. Intuitive and organized navigational categories include ‘Home’, ‘News’, and ‘Contact Us.’ You can place the navigation bar on the top or side of each page for easy access.

Use informative URLs
When users search for a term or phrase, the URL (also called the web address) can help them determine if there is relevant content on that particular page. Which URL do you find more informative?

http://www.onadivabaseballcards.com/article210.htm

vs

http://www.onadivabaseballcards.com/articles/ten-rarest-baseball-cards.htm (…more informative)