So anyone who has mastered the art is unfortunately unable to remember how they did it, or indeed that head-butting is an art. Luckily, despite being novices, The Gorskys have put their heads together to bring you this useful primer. It depends on how you do it. On the other hand, head-butting the school bully until you are unconscious before he drops his pants and pees on your face is just awful. What you need to do is choose a good target.
Grand mothers are good targets.
Super heroes are not. In the interests of family harmony, we do not recommend you choose your own granny. Having found a likely granny, don't just let fly with your face. Head-butting can be quite painful if you do it the wrong way. The wrong way is to flail about aimlessly with your face.