Each of the pages in your website should contain enough unique content, ideally at least 300 words, for visitors and search engines to understand what they're about. The content should be well-written and relevant to your site's topic with your target keywords sprinkled throughout.
If your site contains a lot of highly interactive elements, such as image galleries, movies, or Flash®, consider including a few content-rich but simple HTML pages (such as a blog, for example) as alternatives for mobile visitors and search engines. Because search engines don't "see" the Web the same way we do, pages containing a lot of interactive elements typically display blank to search engine spiders.
For more information, see How Do Search Engines Read My Page Content? and How Do Search Engines See the Web:.