If you really want to be carefull, don\'t use a q-tip, it may leave lint. Go to a photography store, and buy some lens paper (it\'s super soft, lint free paper for cleaning)... or use kim-wipes, or some other computer screen cleaning item.
Then use a non abrasive fluid, I use Swish CRT cleaner (again, it\'s for monitors, but works wonders on camera lenses, or fine optics).
Guaranteed not to mess up clear items
.