So far this making some false story for collecting money or selling book, of course we may do anything for Krishna, but that is supposed to be reserved for very advanced experts in Krishna Consciousness - they know how to catch the big fish without themselves getting wet. So it is not very much advisable to make lies just to sell book. If we simply stick to describing how wonderful is Krishna, then whatever we may lie or exaggerate, that will not be lie! But other things, lies, they will not help us to train ourselves in truthfulness. Lie to some, not to others, that is not a good philosophy. Rather the brahmanas are always truthful, even to their enemies.
Letter to Sri Govinda, 25 December, 1972