A high page rank means two things: visibility and traffic. Before doing anything else think about you meta titles and meta descriptions. Try to write concise, informative and persuasive texts so that (future) clients will know right away what you're site is about.
From the SEO Settings (Admin Interface -> Settings -> Site Settings -> SEO Settings) menu add:
Add a meta title to the home page.
Tells search engines more about the content of the site. The description should be between 70 and 155 characters (including spaces).
Other Tags (optional)
Enter any additional meta tags to add to the site.
Note: Format: key (keywords, robots, etc) - value (string)
Enable Search Engine Friendly URLs
The mod_rewrite Apache extension should be loaded in order for search engine friendly URLs to work.
Home Page Custom HTML
Add custom html to the home page. Add one tag that best describes the website and at least one tag with secondary descriptions.