One one of my dogs use to be quite snappy and use to like to bite ya hands quite hard when he was a puppy. You just have to tap their nose and say no each time they bite ya hands hard and get to aggressive, just tap nose and say no, and keep doing that any time they bite hard, they will soon learn to be more gentle even if they just trying to play. Seems you getting hte hang of it and showing who the boss is though, so progress sounds good.