It's normal and even cute when your puppy nibbles and even lunges at your hand. Since your puppy has been exposed to only other puppies in the litter who naturally play with mouthing and biting, it would make perfect sense why he would assume that playing with you wouldn't be different. But as they grow and their bodies become stronger, what was once cute nibbling eventually turns into uncomfortable or even dangerous rough playing bites. more
I don't teach or recommend so-called "purely positive" methods that allow misbehaving pups to continue misbehaving, instead of teaching them which behaviors are and are not allowed. "Purely positive" is fine for teaching tricks and high-level competition exercises, but NOT for teaching the solid good behaviors that all family dogs need to know, and NOT for stopping behavior problems such as barking, jumping, chewing, nipping, chasing, etc. go here for more
First of all take a treat, hold it in your hand and wrap your fingers around it and no matter how much your dog tries to get at it, bite your hand or paw at your hand you mustn't let him have it. What you have to wait for is the minute that his nose comes away from your hand. That's what you're rewarding him for. He needs to know that he's never ever going to get a treat by biting your hand. How Do You Train A Family Dog ?