If you are a new site, it can be difficult to go after popular keywords right away. I find it better to write many quality articles on very specific keywords than to go after the ones with more search traffic. A great benefit of staying focused with long-tail key terms is that they usually convert better, as well. To help with this, I recommend a tool called HitTail, which drives targeted search visitors to your website by focusing on the most promising organic keywords in your existing traffic.