Good tips so far! Practice makes perfect. How long is it taking you to drill the hole? On a 40 breeder it takes me somewhere around 20 mins or so to drill a clean hole. I use a little pressure once the hole is started, 90% of the hole takes me less than 10 minutes. Then the last 10% takes 10 mins alone. I use plumbers putty to build a dam around the hole and use a hose to slowly flush the hole while I'm drilling. Very slow water flow, but it helps! I also use painters tape to hold the glass in place for when I drill through, so it doesn't drop and chip anything and to try and keep the hole a little cleaner. Keeping the drill even and level is kinda hard, but important! You can do it!!!