Have a read of this article.

http://www.usatoday.com/tech/products/services/2008-06-22-google-search-engine-optimization_N.htm

In it, Matt Cutts a Google Engineer and blogger sums it up:

1. Ask the question 'What are people tying into Google to find me?' When you have the answers, MAKE SURE those words and phrases are on your website's home page.
2. Fill your 'tags' - make sure your Page Title and Meta Description sum up what you are about. No misspellings please!
3. Get other sites to link back to you. Phone around, make sure your best mate has a link to your site and return the favour. (Make sure he's linking to you from a keyword too)
4. Create a blog - or, more importantly, keep the content on your site fresh and keep adding to it. Don't ask 'What can I delete from my site?' ask 'What shall  I add today?' Any Content Management System (CMS) will allow you to do this - and ALL Krann sites come with a built in CMS to turn your website into an online media experience!
5. Register for free tools - Google's webmaster tools (at https://www.google.com/webmasters/tools/home?hl=en) helps you optimise your site with Google - this is part of what Krann Ltd do for you when we optimise your site for Google ranking.