I drill with the plastic bag and use a little water in squirt bottle to keep things moving and contain dust, use just enough to keep a paste coming out of cut. Also follow scaryperson27's suggestion of drilling for few seconds and waiting this will stop too much heat from building up and breaking the glass. Don't worry about using a cordless drill when damp it won't hurt you I've worked in the rain lots of times. The plastic bag will help keep the drill dry and ruining it.