There are two main kinds of search engine optimization (SEO)--Off Page and On Page.  Off Page optimization relies on the links you get from others increasing your page rank.

On Page optimization can include:

• Ensuring that you have unique tiles and meta tags for your different pages and that they reflect the content of the page
• Using a robots.txt file to prevent search engine bots from indexing pages you don't want them to index
• Bulleted lists
• Using "static pages" for each of your pages (pathauto will do this nicely and automatically on your Drupal site)
• Creating a sitemap for the search engines to access