Though I have seen people do this in Excel, I prefer the ability to quickly wipe away, move, change my mind, and finalize my concepts much like a figure artist with a sketchpad. For that reason I recommend a sketchpad or ideally a whiteboard.
I'm going to stick with my earlier example of building out keyword intelligence visuals for SLR accessories since there are a lot of terms and a lot of potential variations for each stage in the intent funnel.
Once you've finished tagging all your keywords for best and intent, there's one additional caveat that I like to add, occasionally, which I call content type. And this is exactly what it sounds like, it's a human element that provides some context around what might be the best path for creating content around that keyword - and while there's a lot of options, I tend to focus on blog posts, aggregate pages, and evergreen pages.
Here's a quick look at what this might look like:
In the above view I have sorted the intent column by Average search volume > Search intent for commercial investigation > Best.
Next we move onto the keyword column to separate which keywords should be targets for organic versus PPC, because all keyword opportunities are not created equal. These are based on a few heuristics but really come down to average bid price versus AdWords competition on the PPC side, and search volume versus organic competition on the SEO side.
Here's a peak at this list tagged for targets:
Where this becomes really powerful is when you start to use this data to drive your content creation and distribution efforts.
Here's a few tips for creating keyword targeted page content:
Now you have a enough data to start making informed decisions regarding your keyword targeting and timing. Using a keyword matrix gives you the ability to quickly refer back to a set of data (as long as you keep it up to date!) to drive your editorial calendar, your on-page content, when and which pieces warrant video, and any other opportunities for keyword optimization.