I think the tap is the most risky and important part of this, but when you drill the hole make triple sure you dont move the drill other than up and down, if you move it to either side you making the hole bigger and not deeper! Also dont lean on the drill, go slowly...
When you tap the hole, treat it like a premenstrual female with fish hooks for fingers is cupping your nuts!
I think jksparky has a very good tutorial on youtube.