The main issue I have with all of these vanishes is that your hand movements do not seem natural. It only takes focusing on the unnatural movements to find the tell of your method. Pay attention to when your hands touch and to how long they are together. After the transfer, don't focus on the hand that had the coin. If the coin isn't there, nobody should be paying attention to it. Read Tamariz's Five Points and pay attention to the parts of how the big motion covers the small. This is a personal preference, but I find hand washing useless. Try to figure out how your hands would move if you were actually vanishing the coin and have the vanish imitate that movement.