In addition you can check whether you are targeting the right audience or optimizing your site to concentrate on the wrong keywords. This page lists a few free tools you can use to save yourself some painstaking work. Some of these tools are offered by SEO firms that have premium services and tools but they offer some free tools which should be enough to start with.
The fist place to start is the W3C markup validation service. This free service checks documents like HTML and XHTML for conformance to W3C Recommendations and other standards. A validated site will be better indexed by the search engines robots and would be easier and readable to users with different systems. Another important tool from the World Wide Web Consortium (W3C) site is the Link checker. Broken links would lower you page rank and can prevent your site from being listed in a lot of the major directories like DMOZ for example. This link checker can save you the meticulous work of checking the validity of each link on your site manually.
Next test on the list is the META TAG ANALYZER this great tool can give you a comprehensive report of your site SEO condition, show you how to improve your meta tags and check your keyword density status. Finding Whether you are targeting the right keyword can be made with the KEYWORD DENSITY & PROMINENCE and checking your site ranking and google placement regarding these keywords can be made at GoogleRankings
if you need a similar tool to find your position at Yahoo you can find it at Seo-guy Seo tools page
if you like to find out approximately how many inbound links you will need to obtain in order to climb your way up to the top 10 google ranking; Iblcheck is the place for you.