I don't have a Yorkie (yet!) but here's what's worked for my Shar Pei, Keeshond (RIP), a friend's Rottie and 2 cats.
When they bite me maliciously (not playing) I give them a firm NO and I take their paw and bite back. Before anyone freaks out, I don't bite hard enough to hurt, just enough that they feel MY teeth. Also, with the puppies, yelping "OUCH, OW" etc. in a really high pitched voice works wonders. It's what their siblings did when they were together. I read that somewhere and it really does work.
If they're mouthing my hand/arm too hard I also say NO and GENTLE.
Hope that helps! |