P.J. Fusco writes a good list of things to look out for when performing SEO on your website.  I only wish I can trim it down to a top-5 list.  Comments?

From http://www.clickz.com/3624560:

1. Are the keywords you're targeting relevant to site content?
2. Are targeted keywords popular phrases used in search engine queries?
3. Do page titles start with your targeted keywords?
4. Does your site employ H1 header tags for prominent content titles?
5. Is your permanent body copy contextually sufficient and keyword-rich?
6. Do text links include targeted keywords that point users to pages within your site?
7. Do you use CSS (define) image replacement in graphical navigation on the site?
8. Do graphics used in the site have descriptive, keyword-rich alternative attributes that are useful for visitors?
9. Does your Web site have a site map with text links?
10. Do the URLs of your dynamic, database-driven pages look simple and static?
11. Does your site have a flat directory structure?
12. Do your site's home page and other key category pages have PageRanks?
13. Is your site listed in Open Directory?
14. Do you routinely list your site in other trusted, human-reviewed online directories?
15. Do all the pages in your Web site have keyword-rich meta descriptions?
16. Does your site have a custom error page?
17. Do the site's filenames and directory names include targeted keywords?
18. Does your site avoid using pop-ups?
19. Is the exact same content visible to both users and search engine spiders?
20. Do you avoid free-for-all linking offers?