Shaun Anderson of Hobo SEO did a good interview with Aaron Wall, titled Keyword Research For Beginners With Aaron Wall.
It's well worth reading. Aaron spends a lot of time "in the trenches" doing real keyword research for real projects. Too many "famous" SEO's only sell services. Aaron is not one of those guys, Aaron knows what he's talking about because he's building and promoting his own sites and making great money do it.