Keyword selection is the most imperative factor in the SEO process. It is is a process of selecting the most “optimum performance” keyword phrases that can help visitors find your site. For any marketing strategy to succeed, it is critical to know your audience and the means to reach them.Various tools are avaliable for analysing keywords.

Following is a tool which shows the results from both wordtracker and Overture

http://www.digitalpoint.com/tools/suggestion/