Google disavow links help remove hurt backlinks that may be causing your PageRank to be lower then it actually should be.
When it comes to search engine visibility the sitemap.xml file as well as a page that includes your site map are really important. These files allow search engine crawlers to have a finely indexed map of your website, the easier you make it for the crawlers, the more they'll like your website. Also a few tools such as Google Webmaster Tools allows you to upload a sitemap.xml file for better visibility.
Don't have Google Webmaster Tools added to your website tool kit? Found how to create a Webmaster Tools account and add your website easily!