Okay. That's a good age - when you get a puppy at 6-7 weeks it is much more difficult.
When she nips or grabs you, pull away and say "ow" in a high pitched voice. She will understand from your voice that she's hurt you, and pulling away is punishment in itself: she doesn't want your hand taken away.
On most puppies that works, but some are a bit too persistent and excited, so you also have a second option if needed. Grab her muzzle in your hand, apply light pressure for 2-5 seconds and say "no" in a deep growly voice. You are not going to be cutting off her breath or squeezing or hurting, only light pressure. Be very very careful with this method that she does not learn to dart out of your reach.