[Lynn]

Use a brand new bit so it will be less likely to walk. Also, being new and very sharp, it will cut quickly so as not to build up excessive heat.

Finally, slip a small piece of rubber hose (like a fuel line) over the bit, leaving part of the bit exposed. That way, when you "break through", if you still have pressure on it, the chuck doesn't hit the paint.

I like the bullet point bits. Black and Decker works just fine on sheet metal.

Good luck.