One of my secret weapons is a paid keyword tool that works wonders for me.
http://askearlabout.com/keywordtopia/link.php
What makes it so valuable is that it is a shorthand way to access the power of WordTracker, without having to pay the high cost. Jonas has been running a special offer for an annual subscription, it may still be in effect. I highly recommend it, I skipped it and have been paying about $20 a month for several years now. It’s been well worth it. If the special is gone, he has been talking about pulling it, don’t fret too much. If key words are valuable to you, you really do need find the words that are about your topic without having the word or two you are searching on in them.
For example I did a keyword search for the term teeth whitening and got back among the results cosmetic dentistry. Try that with the free key word tools.