Oh I know I know...

When picking keywords, make sure you know what your goal is.

If you want to just bring in traffic, look for high traffic attention getting keywords, but if you want to CONVERT traffic, you need to make sure you pick keywords that someone looking for your product (or service) would be thinking about.

For example, if we sold bubble gum and just wanted visitors we could target something like, "hot guys chewing gum," but since we are trying to *sell* gum, it would be a better use of our time to target keywords like, "best bubble gum flavors." Of course, if we were a porn site that had pictures of hot guys chewing gum, the first choice would be better.