Your new puppy is exploring the world in lots of different ways. One way she's learning about her new home is by biting and mouthing everything she can get her ever-loving chops on. While this is normal dog
behavior, it's up to you to show her that while Dog Mouthing her beloved stuffed animal is OK, nipping at the neighbor's toddler is not.
Socialization
Typically, mother dogs and siblings teach puppies not to bite when they are very young. Since we often take our puppy pets home at a tender young age, it becomes our responsibility to discourage this behavior. Ideally, your puppy should be allowed to play with other dogs. Not only is the socialization good and healthy for your playful pal but this is the best way for her to learn where the biting boundaries lie. If she's too rough, her doggie playmates will let her know in no uncertain terms. This can be a very important step as a lack of socialization can actually cause biting. If your dog is always frightened, she is likely to act out in an aggressive manner. The best time to socialize a dog is by the time she is four months old.
Establish the Hierarchy
Dogs are pack animals and every pack has a leader, or "alpha dog." You must establish yourself as the alpha dog right from the start in order to make the behavioral boundaries clear to your new pack member. If you establish trust and respect in your dog, she is much more likely to 
abide by your rules. This is especially true with Dog Mouthing and biting.
Battling Biting
First and foremost, never hit your dog when reprimanding her. This will only encourage biting. The more your dog feels safe and cared for, the less likely she is to engage in aggressive behaviors. While reprimands may help, socialization is key to putting a stop to this behavior. Be consistent. If you're trying to eliminate Dog Mouthing and biting, never tolerate it. Allowing it sometimes but not others will only result in frustration. Don't hold a grudge. After you've firmly reprimanded your dog (remember, no hitting), then go back and bond with her. It's the Dog Mouthing you didn't like; you still love your dog.
An ounce of prevention is worth more than a pound of cure when it comes to Dog Mouthing and biting in dogs. If your dog's biting has become more than you can handle, it's time to seek the help of a training professional.
