Google Webmaster Tools has a great article with tips for creating a Google-friendly site. We would encourage you to read the full article, but here is a summary of the key points.
Give visitors the information they're looking for
Provide high-quality, relevant content on your pages, especially your homepage. Remember to target your content towards what real people will find most helpful rather than trying to write for search engines.
Make sure that other sites link to yours
Natural links to your site will develop over time when other sites find your content valuable and think it would be helpful for their visitors. Unnatural links to your site (such as link schemes and doorway pages) are specifically intended to make your site look more popular to search engines. Google says that only natural links are useful for the indexing and ranking of your site.
Make your site easily accessible
Build your site with a logical link structure. Every page should be reachable from at least one static text link.
Things to avoid
- Don't fill your page with lists of keywords, attempt to "cloak" pages, or put up "crawler only" pages.
- Don't use images to display important content. Google cannot read text that is contained within images.
- Don't create multiple copies of a page under different URLs (web addresses).
- Don't feel obliged to purchase SEO services from a third-party. Legitimate consulting firms can improve your site's flow and content, but others may use questionable methods that could harm your ranking. See our related article: Considerations before paying for SEO services