Well, the first lesson is, this pointy bit [he points at it with a smile] goes into the other person.

[Okay, that might not be his best joke, but he's used to bantering with people who have known him his whole life and would find it hilarious.]

Until you've learned to be more comfortable with it, if you need to use it, aim for the gut. Gut wounds are very painful, they're extremely disabling, and hard to heal.