Here are 10 essential tips that will make sure your site is ready to go when Google decides to send their spiders your way. Following these practices will inevitably result in a better indexed, better ranked, and better site overall.
Without further adieu:
1. Use "alt" and "title" tags for your images.
2. Always title your links.
3. Make your URL's "pretty" using mod_rewrite. (ie: /blog/9/ v.s. /blog.php?id=9).
4. Write valid code.
5. Write semantic markup.
6. Don't use Flash unless you know how to.
7. Use 301 redirects.
8. Make image based navigation fall back to text links.
9. Write keyword rich content.
10. Don't try to cheat. You'll get banned.