Stop a dog from biting on you; the tough times!
When it seems like nothing is working at stopping your dog from biting:
I came to train this puppy for pulling on the leash but a couple of minutes into training I realized that there was a worse behavior: biting. The family had two children under 5 years of old and this puppy was going to be about 70-pound dog very soon. I noticed that the boys would tease the puppy and he would get mad and bite them. This behavior is very dangerous as one day the puppy will bite too hard and would get into serious trouble that could include being deemed as a dangerous dog or worse be euthanized. I knew that this was a priority.
Normal methods did not work with this dog right away. I first had to instruct the parents about supervising the children and the dog. I went through training with them first on how to help the boys understand that teasing the dog was not a good idea and that they should not play with the puppy when he is biting them.
When I got to the puppy, even just touching his collar made him become a complete maniac where he started twisting and biting and growling at me. But as I always say, you have to just out-stubborn the dog. I stayed calm and waited for any moment of not biting so I could reward him. I think I worked on him for almost 45 minutes before I was able to hold his collar without him biting me.
Sometimes it is going to feel like you are not getting anywhere or the behavior starts getting worse. But you have to stick your plan and not give in. If you are getting hurt I suggest wearing oven gloves to protect against the sharp puppy teeth. Get your dog tired before you start handling training. Or work with a positive reinforcement trainer to help teach your dog that biting is never okay.