Use only well-formed HTML code in your pages. Ensure that all tags are closed, and that all links function properly. If your site contains broken links, search engine spiders such as Googlebot and MSNbot may not be able to index your site effectively, and people may not be able to reach all of your pages.

If you move a page, set up the page's original URL to direct people to the new page, and tell them whether the move is permanent or temporary.
Make sure search engine spiders are allowed to crawl your site, and are not on your list of web crawlers that are prohibited from indexing your site.

Use a robots.txt file or meta tags to control how search engine spiders and other web crawlers index your site. The robots.txt file tells web crawlers which files and folders it is not allowed to crawl. The Web Robots Pages provide detailed information on the robots.txt Robots Exclusion standard.

Keep your URLs simple and static. Complicated or frequently changed URLs are difficult to use as link destinations. For example, the URL www.example.com/mypage is easier for search engine spiders to crawl and for people to type than a long URL with multiple extensions. Also, a URL that doesn't change is easier for people to remember, which makes it a more likely link destination from other sites.