TOH and others have shared their experiences, good advice and "Spark Meister" information, but there's not so much detail I'm finding on forums & archives on best ways to clean spark plugs.
My vote goes for pneumatic, media-blasting, spark-plug-cleaning specialty tool, that does the quickest and easiest job for me.
If you shop around in the usual places you can find them for around $13 shipped; downside is that you'll need an air compressor to run it; on plus side, pneumatic's "clearing position" blows media out from within plug's electrode cavity.
They do make 12 volt dc-powered spark-plug-cleaners, which bypasses need for an air compressor. Just clamp power leads onto your battery posts, insert spark plug, push button and you're good to go. Downside, you have to be careful there's no media what gets stuck in plug's electrode cavity, or you'll need to use a wire and dig it out.
On internet forums, where everyone appears to espouse opposing opinions and prefers debating the "which-ness of why," something tells me most'll agree, allowing abrasives inside engine's cylinders has no positive useful purpose! :-)
I have come up with a list of about 15 different ways people on forums reportedly've used in cleaning their spark plugs (most of which I've tried at one time or another), but I've yet to find anything as easy and convenient as specialist tool made specifically for cleaning spark plugs.
Difficult rationalizing reasons NOT obtaining a new tool, and what's NOT to like about that? ;-) lol