“Provide high-quality content on your pages, especially your homepage. This is the single most important thing to do. If your pages contain useful information, their content will attract many visitors and entice webmasters to link to your site. In creating a helpful, information-rich site, write pages that clearly and accurately describe your topic. Think about the words users would type to find your pages and include those words on your site.”
Sometimes we forget this. In an attempt to make our sites look really nice a lot of attention goes into creating homepages with loads of images. The site I am currently working has a homepage made up predominately of images for campaigns that they are currently running. As a result there is very little content for Google to index. Plus what content there is is campaign focused, thus it changes all the time.