Google's Search Engine Optimisation Starter Guide
Google released a document in late 2008 outlining best practices which will make it easier for search engines to both crawl and index a website's content.
The document can be summarised as follows:
1. Create unique and accurate page titles.
2. Use the "description" meta tag.
3. Improve the structure of your URLs by creating descriptive categories and filenames for the documents on your website.
4. Make your site easy for humans to navigate.
5. Write descriptive anchor text.
6. Use heading tags (e.g. h1) appropriately.
7. Optimise your use of images by creating descriptive distinct filenames and "alt" attributes.