Hey, how are things up in Dickson?
The outside is really easy, since it's painted plastic. Unless you have a custom paint job, that you'd treat with the care you would a car or bike's paint job, just use good ol' window cleaner. I like the ones without dye, like Armour-All or new Clorox Green Works (which uses all bio-based ingredients). Paper towel or cotton cloth on the helmet, but no paper towels on the visor, since they can create tiny scratches over time. (But, ya know, they do sell replacement visors! I recommend getting an orange or yellow one for daytime riding.)
The harder part is the road grime and bugs that will eventually get lodged in the vents. The good thing is that when bugs dry up, there's not much left. So Q-tips and canned air will clean those out.
The inside, if you can remove, can be hand-washed in the sink with anything from Tide to shampoo. But if you wear a Slicks or do-rag, it wil stay much cleaner anyway.
I really appreciate the opportunity to answer a non-technical question! Come Sunday, I'll be speeding past your neck of the woods on my way to Wild, Wonderful West Virginia. Sorry I won't have the chance to stop by and meet you in person, but hope to do so soon.
OH, both my helmets are Sho-eh-ee. I love my Syncrotec (I've had two of those, someone stole my first one), and am tempted to drop it so I can upgrade to the new Multitec (just like Alton Brown wears!).