Add meta tags and a keyword descriptive title tag to the sitemap. The focus of your title tag and metas is a general, non-specific overview of the theme of your entire website. List every link to your inside pages, preferably root level pages for your strongest chance of crawling by spiders. If your site is extremely large, categorize the links, and list top level pages only. Robots have a limit on how many links they'll pursue.
Every word counts, so avoid hype and sales jargon.
In addition, linking certain words to inside pages is helpful. The first 200 words are critical. Put a text link to it at the TOP of your homepage. Additional text links to the sitemap in the navigation sections of your inside pages are fine. Submit it to search engines ONLY - not directories.