I have a drill press and a plastic (Tupperware/Ziploc) container. At the bottom of the container, I put a thin sponge or plastic protective wrap– the kind that is about 1/4 thick and is often used to pack glass. I fill up the container with water and put the glass to be drilled into the container. This provides me with enough water to keep the bit wet and enough padding to keep the glass stable and provide a stop for the bit. Otherwise, a ring of putty or Playdoh and water work on larger items.
I do know that slow, even and steady drilling works well for me. The key I have found is to have even pressure and to pay attention to the thickness of the glass. I’ll mark the depth of the glass on the drill so I know when I am coming to the bottom. I’ve been able to get through 1″ of glass with some patience.