- Make It Complete - A sitemap should contain the complete set of user pages on your website. Use several sitemaps if necessary.
- Register Your Sitemaps In Your robots.txt - Use the sitemap command (for example, sitemap: http://mywebsite.com/sitemap1.xml, sitemap: http://mywebsite.com/sitemap2.xml...) in your robots.txt file to tell crawlers where to find your sitemaps. This is more efficient than submitting your sitemaps to crawlers, since bots crawl and re-crawl your robots.txt often. Moreover, you will not need to resubmit your sitemaps if you modify them.
- Not A Substitute To Bad Navigation Links - Although complete sitemaps will help bots crawl all your pages, if these pages are not accessible to users via proper navigation links, they will not be indexed well. Sitemaps will NOT increase their visibility and SERP ranking. Do invest time in fixing navigation links on your site. It will bring more return than a complete sitemap itself.
- Set Higher Priority To Pages Containing More Internal Navigation Links - A higher sitemap priority does not influence a page's SERP at all. It only tells search engines which page you believe it should crawl first. If you have a big sitemap.xml, they may not want to process all your entries, they will pick those with a higher priority first. By setting a high priority (more than 0.5) to your site's main page and those having the most navigation links to other pages, search engines will process them first for indexing, meaning users will see them first, which increase the probability they will navigate more on your website, which will increase ranking. Seduce end users, not Google!
- The LastMod Tag Is Your Friend - If you don't cheat with the lastmod tag for each page, I have noticed Google responds well to these. In other words, don't forget to update them when you modify page content.
- Hardly Use the ChangeFeq Tag - Unless you are 100% sure you can provide valid information about the change frequency of your pages, don't use the changefreq tag. And if you do, make sure you deliver on this announcement. Don't try to manipulate search engines with change frequencies, it does not work. Let them figure it out itself. Remember that no information is better than bad information!
- Patience Trumps Sitemaps Fiddlings - If you implement all the above properly, search engines will respond faster than if you try to fiddle your sitemaps over and over in order to improve crawling and indexing. In some cases, too much fiddling delays the processing of your pages. Your site may be considered as unstable and therefore not a good user experience.
Sitemaps do not compensate website weaknesses, they only support well designed websites!