I was using KEI as a rough measure of keyword competitiveness, mainly because there's a cheap tool to allow me to compute KEI for phrases in bulk. Now that I've narrowed my list of potential keywords, I can use a tool like SEOchat's Keyword Difficulty Check to evaluate the competitiveness of each term by hand.
I copy my last visualization and replace the KEI measure with my new Difficulty measure. I tell Tableau to ignore the keywords for which I didn't collect a difficulty score, and almost instantly I have a new visualization.
Just looking at the bigfoot terms for now, it's clear that "bigfoot sightings" is the dominant phrase in search volume. That dark red color also tells me the term is extremely competitive – Joe won't be ranking for it anytime soon. For now, let's hide the phrase "bigfoot sightings". Tableau rescales my graph and new insights jump out.
"Bigfoot sightings" was too competitive for my liking, but there are some variants that look very promising. "Sighting of bigfoot", "sightings of bigfoot", "first bigfoot sighting", "new bigfoot sighting", "Oklahoma bigfoot sighting", and "recent bigfoot sighting" are all very nice shades of green. These phrases are closely related, so it will be easy to create plenty of quality content to target all of these phrases. And the best part is that all that effort will be building up relevant authority for Joe's eventual run on the big-money phrase, "bigfoot sighting".
Oh, and there's even a misspelling that looking interesting. "Bigfoot sitings" doesn't look competitive at all – one highly optimized page might net me a few hundred extra visitors a month.
"Bigfoot organization" and "bigfoot photo" also stand out as highly trafficked, very valuable, but less competitive phrases. I make a mental note to evaluate them more carefully later. When I get a chance, I use SEO for Firefox to examine the competitive landscape. The top few results on Google have fairly high pagerank and a lot of incoming links, but the results from #5-#10 are unimpressive.
Joe is an avid blogger, has a very active forum on his site, and hasn't done any SEO at all until now. I think he could be a contender in search – we'll keep both those phrases in mind.
And just like that, we have a keyword strategy for the "bigfoot" category. We've got a nice set of niche keywords to attack for some immediate traffic, two somewhat more competitive terms to shoot for in the medium term, and one dream phrase ("bigfoot sightings") that we'll be building SEO karma for with all our groundwork right now. I can repeat this process in just a few minutes for "dragons" and "unicorns", and we're almost good to go.