Well...11 tips actually...you get one extra for free...ok, so they're all free...anyway...
I recently joined Smorty, a blog advertising brokerage, and found this easy guide to SEO on their site which has 11 great tips for search engine optimising your site.
It's nicely written (especially for beginners) and has lots of links to great, practical tools to help you optimise your site such as a keyword density checker (has a nice keyword cloud view), duplicate content checker.
I particularly like their keyword suggestion tool which, given a URL, identifies the theme of the page and then suggests keywords on the same theme, ordered by the volume of searches per month for that keyword. Very nice.
The article is well worth a read. In fact, I wish I'd written it myself!