Finding new keywords
You will always want to be alert to new keyword opportunities. This is the "expansion" phase of your keyword development. New products and product model numbers will become new keywords as they are released to the market. New technologies create new keyword opportunities at an ever-increasing pace. New laws create new keyword opportunities as they are passed. Stay on top of these keyword trends and you'll further edge out your competitors.
Eyeing the competition
One way to find new keywords is to keep an eye on your competition. What keywords are your competitors utilizing for the important pages of their website? Is your competition advertising new products and services? If so, it may mean that they've found a micro-niche within their market that you can harness as well.
You can also use one of several keyword spying websites. The website Spyfu (http://www.spyfu.com) touts itself as a resource that empowers you to "spot new SEM/SEO opportunities and outsmart your competitors...