Backlinks, backlinks, backlinks! Get other sites to link to you. Better yet, get them to link to you with your target keywords as the anchor text. Backlinks are the most important factor to off-page SEO. As far as on-page SEO, also ensure use of CSS'ed H1 tags to emphasize your important keywords on each page.

Content, content, and more content. And many backlinks too! Use your keywords as anchor text. As you may not be aware, Meta Tags have little value to Google. Yahoo and MSN use them but they wont get you too far. Title tags are super important though. And who could forget freshness? You gain a competitive advantage if your pages are constantly changing - some strategies include incorporating blogs and feeds.

Read my brief tutorial at: http://www.daniweb.com/tutorials/tutorial20471.html for a better scope of how to compete in the search engines.