Summarize the following:
You want to drill slower when you are drilling into hard materials; you can find charts online that provide recommended drill speed for different materials, including glass. Chuck a small bit into a variable speed motor drill. Make sure it is secured tightly. It is best to start with a bit maybe about 1/8" or 3/32" in size. You only want to create a dimple in the glass at first. Then, remove the cardboard or tape and drill faster, at about 400 rpm. If you drill too fast, your drill bit could cause burn marks around the tip. If it seems necessary, swap in a larger bit to enlarge your initial hole. The first hole is a "pilot" hole. It will guide the subsequent larger bits as you work your way up to the size of your finished hole When drilling glass, you should keep the drill at low or medium speeds. When you are close to breaking through, slow it down even more because this is when the glass can be the most fragile. If you press too hard on the glass with the drill, you could crack it. Hold the drill perpendicular to the glass so that you prevent chipping. You'll want to use lighter pressure if you're new to drilling to make it less likely you make a big mistake. Another approach is to drill half way through, flip the glass over (carefully) and drill through the back side of it until you meet the other hole in the middle. This is very important. Pour a little oil or water on the area that you are drilling. Water is the most common coolant used on drill bits. You will need to use more coolant if you are drilling a harder surface. The coolant will keep the drill bit or saw and glass lubricated and cool. If the glass gets too hot while drilling, it can crack and break. Coolant should be applied both before and during drilling. You could put a bottle with water in it and a small hole in it at the drill hole. It will trickle out and onto the hole as you drill the glass, cooling it. You could also spray a mist of water around the drill bit instead to keep it lubricated. Again, remember to be very careful of electrical cords and water. Try putting the water in a squirt bottle and apply it as you drill. If white powder forms as you drill, you should apply more coolant, and slow the process down. You could also place a wet sponge under the glass as you drill to act as a coolant.Or you could cover the glass with a small amount of water before drilling - basically put it in a shallow water bath in your container.
Start drilling at a very slow rpm. Lighten up the drilling pressure and speed even more so when the drill tip is close to breaking through the glass. Use coolant so the drill bit doesn't get too hot.