Is there a magic-wand to wave if I want to improve my position for a single keyword? Is it a balance of keyword density? Meta? Age? All of the above? Oh, and HI, just signed up!
It's about your content and your content matching the incoming anchor text of links that point to the page on which your keyword resides. Simple as that.
You can improve your position for a single keyword and is Possible but you have to give more effort and more patience. Focusing on content and backlinks you will get success.