As you know, Google looks at 200 aspects of optimization when rankings sites in their results. Some of the more important are PageRank, inbound links and title tags. Addressing these issues first will help out a lot in improving your google search results.
1) Title tags – Should be focused and unique to each page of the site.
2) Broken links – Google webmaster tools shows broken links from other sites that link to you. If you changed a file name or now you use index.php and they linked to index.htm this error needs to be corrected. It is possible to use an .htaccess file to correct some of this.
3) Link text – All internal and external links should use keywords. Don’t use “click here”
4) Build relationships with other webmasters who will give us good links.