I first practiced by tying a cigarette to the neck of a balloon, figuring if I could hit the cig without hitting the balloon I'd be okay - and so would my vic- um, student.
Of course, all the other students referred to him as "balloon boy", so that didn't help matters much.
I never put a mark on him in over 50 demos, though.
... HE developed a facial tic, but I'm sure it's totally unrelated ...