No, unique content is the main factor. Playing with kewords may damage your site's ranking. I'm oonly focusing on Meta Title and Meta description.
Always make sure the keywords you use have low competition and a reasonable amount of monthly searches with Google. If you follow that path and use the keywords for your article titles, squidoo lenses, hub pages and for also placing them in the title tags of your website/blog index page then, you're well on your way to more traffic and potential sales. Mark