Axel,
so far, I'm still learning. the best lesson so far is - on tough material, go slow, and don't try to chop off too much in one go!
Sounds silly, but by following those rules, I don't send drillbits flying across the garage.
I need to get some front panels to practice on from guitar center tonight - once I do that, I'll put some XLR holes in etc, just for practice.
/R