Use Traffic Travis or other tools such as Google trends/insights
SEMrush(my favorite, commercial)
Ubersuggest(free keyword suggestion)
WordTracker(commercial)
Keywordlizard(Free AdWords Keyword Combination Tool)
You can use SEOggestor as alternative
I use this one to find out more useful key phrases
http://lsikeywords.com/
The former Google keyword tool sucks, and I am looking for an alternative.
