The average spectator wants to believe you. You must believe that you actually made a coin disappear. If you do not believe it has vanished, then you will disappoint your audience. Your audience will not believe you either, and you will end up antagonizing your spectators.
Both timing and misdirection are indispensible to a magical performance. You may be able to produce or vanish an object using one or the other. But to create an illusion, you must combine them perfectly.
The strongest misdirection is provided by looking directly at your audience, singular or plural, and not at your hands.