This is where webmaster tools come in handy! There is so many tools that can help you clean up and improve your site like: Submit a Sitemap - This tool allows you to submit a sitemap in webmaster tools database to tell Google about pages on your site that they might miss. Crawl Errors - This tools shows you all the crawl errors on your site that can cause your site to drop of badly. (Crawl Errors are pages on your site that has links to them, but they don't exist anymore.)
The Keywords Tool - This is an amazing tool. It helps you see your website through Google's eyes. It shows you the keywords that is mostly used in your sites content and should give you a clear indication of what the site is about. If it gives you weird keywords you know you need to step up your keyword density so Google knows what your site is all about.
The Last tool I want to bring out is The HTML Suggestions Tool - This tool lets you know if there is any content issues with your site, whether it is duplicate content, missing content or problematic title tags, so you can fix it right away.
This is only a few of the great tools on Webmaster tools that helps you kick your website rankings up to the next level.