The most important thing to focus on when writing content, for SEO purposes or otherwise, is to provide perceived value to the viewer. Google has stated that meta keywords aren't even looked at and the same for Bing. Of course, insert keywords in your content that relate to what you'd expect a Google or Bing query to be as it relates to your site, but don't overdo it. I always recommend performing some type of research to discover the best keywords or keyword phrases related to the topic of each page on your site, and then make that flow with the content.