“The anateur works until they get something right. The professional works until they can't go wrong.”
“An amateur practices something until he gets it right.A professional practices until he can't get it wrong!”
“Amateurs train until they get it right. Professionals train until they cannot get it wrong.”
“Get a good idea and stay with it. Dog it, and work at it until it's done right. ”
“An ordinary archer practices until he gets it right. A ranger practices until he never gets it wrong.”
“Take a note: it usually works better if you wait until I do something stupid before getting mad at me.”