I wrote a post for newbies in Search Engine Optimization (SEO) for a customer. I thought I might as well post it here.

The main goal of this document is to give the Googlebots easy access to your website, and make your content readable and relevant. The following could significantly improve your visibility on Google.

General

• Add the website to Google, periodically (say, every half year or so);
• Construct a Google Sitemap, and add it to Google;
• Make sure the web server supports the If-Modified-Since HTTP header. This feature allows the web server to tell Google whether any content has changed since a Googlebot last crawled the site.
• Make use of the robots.txt file on the web server. This file tells crawlers which directories can or cannot be crawled. Make sure it's current, so that it doesn't accidentally block the Googlebot crawler.

Code

Googlebots read code. Therefore, readable code is very important.

• Use valid XHTML 1.0 or higher for notation (this will make it nice and easy for Googlebots to read);
• Use an external CSS to apply the complete formatting of the website, including structure and visual design (so use divs instead of tables for formatting);
• Use a proper XHTML list for navigation items (this improves readability of the code);
• Do not exceed 100K file size for the complete page;
• Try not to use frames, javascript, DHTML or Flash unless it is absolutely necessary;
• In general, if the website complies to the WCAG standards, its readability is maximal.

Content

Next to navigation elements and images, the textual content of a page is what Googlebots read to determine page ranking.

• Increase the number of appearances of the most important keywords in the content of a page (increase keyword density);
• Make sure there are also synonyms available inside the page’s content;
• Make sure keyword stemming is available inside the content (Stem, stems, stemmed, stemmer, stemming, stemmist, stemification);
• Make sure that these words are shown within b, h1, h2 or h3 tags to show their importance;
• Put the keywords in the “title” meta tag;
• Put the keywords in the “keywords” meta tag;
• Put the keywords in the description in the “description” meta tag;
• Use plain text instead of text on an image to get a message across (Googlebots can’t read text on an image);
• Provide text alternatives for visual and auditory content (so, for every image, use an “alt” description inside the "image" tag);
• Link to the page from other pages and websites, using the important keyword as a title of the hyperlink (try to get the website referenced on as many other websites as possible, but this also goes for internal links).
• Trace links to external websites in the content (validity, but also try to link only to sites that have a good page rank themselves);
• Refresh content as much as possible, but only for relevant changes