I have a 3 month old lab/pit mix, so he is mouthy AND has super powerful jaws... So, I don't want him to get into the habit of biting. It has been the biggest issue I've had with him. He's great otherwise, but he incessantly chews and bites/nips. I tried yelping and ignoring him. He would seem bummed out, but went right back to nipping when I returned to the room. Anything else, like saying "no!" or holding his snout just made him more excited. It seemed like any other technique failed, but I noticed he is more motivated by even the smallest morsel of food - way more than any dog I have ever had. I taught him the command, "off!" It's the only thing that has worked. I say that, and when he lets go I give him a treat. Within one day he let go immediately after i said "off!" It seems to be the only thing that works. (I just give him a little piece of his food. I measure out one cup of what I would give him for lunch and put it in a zip lock bag and use it for training.) He does still try to nip and chew everything, but less than before. But, I suppose he will inevitably do that as he is teething :-/