For some reason that I can't articulate, I hate using the word "no". I usually say "uh, uh", or if I want to interrupt some behavior, I use "hey".
Newfs can shut down quickly if they are reprimanded constantly. I prefer to give them some kind of alternate behavior to do. For example, if they are biting, I give them a toy. If they are jumping, I ask for a sit or down. Kids or adults can tuck their hands in their armpits to discourage both biting and jumping. Sits and downs would have to be trained first and reliable. If the pup is playing inappropriately (too rough, biting, etc.) leave the room. If she's pulling on the leash, stop dead in your tracks and don't move forward until there is slack in the leash. If you are consistent, the dog will quickly learn not to bite, jump, pull, etc.
Be sure that the whole family is on the same page. It's not fair to let her roughhouse with Dad and then be mad when she treats the kids the same way. The kids will need to be taught to not encourage the pup's bad behavior, especially if they are young children. Have a family talk about what you expect and what they can do to help. Make a list of things you want and don't want the pup to do. Don't forget to let friends and other family in on your plan, too. Guests who let the pup jump on them are not helpful, so clue them in before they meet puppy for the first time.
One of the problems that I often see is people who are quick to correct or reprimand and do it often, but who fail to let the pup know when she's doing something good. As you have already found out, praise is your best tool. Give your puppy something better to do when she's naughty and be sure to praise her when she is doing what you want. You should be praising more than correcting. She should quickly learn what is appropriate behavior that way.
A hard stare is more of a threat of impending harm than a correction. You want your pup to love looking you in the eyes, not fearing it. And you want to teach your puppy a "watch" command early. You can hold a treat to your nose or between your eyes for starters, then gradually eliminate the treat. It should be something she enjoys doing and more importantly, it is the foundation for all other training to come. Practice it often and keep using it as a valuable tool throughout her life.
Newf puppies are at best a challenge, but one that you can meet with patience, consistence, and positive reinforcement. After tearing your hair out, they all of a sudden become the best dogs ever! But it's up to you to keep them on track.
If you haven't signed up for a positive reinforcement puppy class, now's the time. The opportunity for socializing and the fun of training need to be addressed right now. The sooner she can get in, the better, and many instructors will take pups as young as 10 to 14 weeks if they have had some of their vaccinations. If you need help finding a trainer in your area, check out APDT.com. Go watch a class if you can, before you sign up, so you can get a feel for the instructor and his/her methods. You don't want to enroll in a class that encourages jerking your dog around. Puppies, especially, are too sensitive for that, it's harmful to their bodies and psyche; and it will spoil the joy of training for both of you.
