Exercise One: Personify Your Inner Perfectionist.
I recommend giving your perfectionism its own name and face.
Can't picture this inner critic? Start by thinking about a mistake you've made recently. Let the voice of the oppressor berate you ("You dumb, clumsy, fat, boring…" etc.). Listen: Does that voice sound familiar? Does it belong to your wicked stepmother, your boss, your ex-spouse, an amalgam of your least-favorite movie critics? Try to summon a visual image of the tyrant. Scribble a picture of it, and do something insulting to this picture whenever your perfectionist acts up. In time, as you neutralize the destructive power inherent in this aspect of yourself, you may well lose all fear of it.