As with all training methods, they vary, but I had a situation with Lou, our rott/lab, where he would become hyperactive every day when I came home. This was when he was a teenager. He would wait until my back was turned and nip the backs of my arms between my elbow and armpit. I had terrible, black bruises all over and I just didn't know what to do. I consulted books, etc., but nothing seemed to work...spray bottles, saying no, ignoring him and turning away, folding my arms and looking up at the sky...he kept nipping me.
So, I called an animal behaviorist who charged by the hour. Now, I can pass her advice forward for you. Perhaps it will work as well as it did for us.
She said to firmly grasp the puppy's muzzle, as you would grasp the railing while climbing stairs. Curl your fingers around the snout, so that your thumb and probably your ring or middle finger touch the canines...thum b touching top canine on one side of dog's mouth, ring/middle finger touching top canine on opposite side of mouth. Then, step one, apply pressure/squeeze gently so that the skin on the pup's upper lip presses lightly into his/her own canines. While squeezing gently say, "No biting!" The trainer said there are basically four steps to doing this...we only had to go to step one, which is the least amount of pressure. Lou stopped grabbing me and leaving those terrible bruises. It was so easy. If he had not, then the next step would have been to apply more pressure. Some pups will snap again after you let go of their muzzle, and that's when you grasp again and apply slightly more pressure and say, "No biting!" It is mildly unpleasant for the snapper, so the idea is that they will stop doing it and it is supposed to be similar to what their mother would do during "bite inhibition". Any behaviorists want to help out? This is just what worked for us.