1) Don't use JavaScript or css navigation. The SE's can’t crawl it.
2) Don't use session id's in your URLs. These can create duplicate content problems.
3) Avoid using more than one parameter (or ID) in a url
4) Better yet, eliminate parameters entirely by using static links
5) Submit an XML sitemap to Google sitemaps and Yahoo Site Explorer
6) Create a physical sitemap
7) Create a Robots.txt file that defines your sitemap and lists exclusions
8) Don't use JavaScript or css navigation. The SE's can’t crawl it.
9) Don't stuff keywords in your primary navigation. Site wide links are devalued.
10) Link to your SEO landing pages contextually. In other words, within a decent size body of text.