Microfiber cloths are the way to go for cleaning/drying a shield.
This little may be the best money I've ever spent on a moto accessory - I've been using it for almost 2 years now:
http://www.aerostich.com/catalog/US/...w-p-16686.html
At home, I'll hand wash the shield with dish soap, and use the cloth in the kit above to dry it. On the road, it's invaluable. I lost it for a couple of weeks, and was amazed at the constant struggle to keep my visor clear of bugs/dirt/gunk.
