I find Palmolive is the best soap in this situation . just make sure it's the pink one with 2% lanolin and 6% Sodium Hydroxide . And stay away dehydration palm oil .
Just pulling your chain ; It doesn't matter the kind of soap you use to wash you hands nor does it matter what kind of towel to use to dry them , as long as it's a clean one .
Hold your coins by the edges and you'll be fine .
Proud Member of The Black Sheep Squadron !