Puppy Bite Inhibition
Everyone who gets a new puppy gets a sample of puppy teeth! Just remember that puppies are pushy and aggressive by nature. That's normal. They play with humans the same way they play with other puppies. They have learned some manners from their mother and littermates, but you are a new puppy to them. They have to learn some things all over again, and that includes learning "bite inhibition" -- biting hurts!
When you play with your puppy and she starts biting your hand you should yelp loudly, just like you're a hurt puppy (this will startle your puppy and usually make her stop). Believe it or not she knows what this sound means. This is the same thing another puppy does when the playing gets too rough.
Then, move away from your puppy and stop playing. Have nothing to do with her. Turn your back on her. Ignore her completely.
Wait about five minutes.
Now it's safe to pet her and play with her again. Do this a few times and your puppy's biting will diminish. If she bites again or plays too rough, do the same thing again. Yelp. Ignore her. Have nothing to do with her when she does it.
Make sure to pet and praise your puppy when she is playing calmly and gently. She'll figure it out fast. If you see your puppy start to mouth you, watch her carefully. She may instead yawn. This shows that she has learned that she is not supposed to bite and she has done something else with her mouth.