Check Crawler error in webmaster tool. Design your site according to google web master guide and create robot.txt, sitemap file. Put relevant & proper title, description, keywords in metatag . use alt tags when you use image.use h1 keyword integrated tags. keep the internal links with suitable keywords. don't use hidden texts or links. avoid keyword stuffing . If you use JavaScript, DHTML, images, or rich media such as Silverlight to create navigation and links, Googlebot and other spiders may have trouble crawling your site. Make sure your content is relevant and useful.