My 12 week old female GSD has an issue with biting.

Telling her "No" has not worked.

I have tried to tell her "No" and then give her a toy and praise her for biting it, but that doesn't work either. She will bite the toy for 2 secs then go after my hands again.

Now I have tried to grab the scruf of her neck, give me a shake, and tell her no... but that just get her more worked up and she tries to bite more or bite even harder.

I have also listened to the podcast where you are told to get in the pussies face and in a deep voice tell it to "knock it off". This has caused our puppy to show her teeth and bite harder as well.

Now, she isn't biting as much now as she did a couple weeks ago. She is 30lbs now and I need this to stop before she gets bigger and could potentially hurt someone with a bite (whether it is playful or not).

Is this a play bite issue, or is she trying to show dominance over my fiance and I?

If it is a dominance issue, can you show me some links that will help me get her to learn her role in the hosue?

BTW, I make her sit before going outside as well as eating. She is also the last person to enter and exit the house.

Does she even know what 'no' means yet? It's not bred into the dog's mind; you need to teach it.

When she bites you, YELP. Make a high pitched "OUCH!" noise. She understands this (the tone, I mean -- not the word) because her littermates would've responded the same way to being bitten too hard. The deep voice is a growl, and may be thought of as a play growl -- think of the deep grumbly noises puppies make when they're wrestling each other. A growl means, to a puppy, 'let's keep going'. The yelp means, 'you took that too far'.

I don't think this is dominance, I think she's just not aware that your skin isn't as forgiving as her littermates' and she needs to learn 'bite boundaries'.

What is the correct way of teaching her the meaning of "no".

I read your thread
I believe your question was how do I get my pup to stop biting?
What does "No" have to do with it!
And "Dominance"?

Let me put it this way,
Do you remember a time when your mothers request to "put on a shirt" was an insurmountable task?
Do you know how many behaviors have to be committed to memory to successfully complete this task?
Try writing it out on paper!

More to your question
I believe you want your dog to know "NO" as stop biting
Well what about "NO" don't jump up
Or "NO" don't eat the pizza
Or "NO" get off the couch
...Do you see my point?!

"NO" is a simple phrase that means stop
Your dog is going to have to learn to stop in various locations and situations
The word does not transfer for one situation to the other, yet!

I'm assuming you got this pup as a pet, not for Dog Sport
All German Shepherd pups bite; I'd be worried if they didn't
Walt Disney lied
Manage your time with your dog!
Quality time vs. Quantity!
Use your crate!
Do you have a pen?
Do you have a fenced yard?
Try leaving a leash on your pup, one they can't chew!
Grab the leash not the dog!
Tried using a Halti?

Your pup is only trying to initiate play with you.
Man, do they have sharp teeth!
Wear appropriate clothing.
They sell it here; it's called a bite suit, just joking!
It takes a while to direct this drive to a tug, purchase a long one, so you can keep your hand out of the way
Short sessions, end when the dogs excited, put the dog away.
What they're doing, is what they're learning
And you thought you were trying to stop this behavior!

This is, after all, how a pup would wrestle with another pup
Remove it from this behavior pattern
Teach them how to interact with you
Don't be too rough, you can hurt them!

Try tying them to the leg of a couch, when you’re in the room
Give them something to chew
Teach them you chill out over there and I'll chill out over here
End when the dogs calm

Personally I never correct biting or jumping up until I'm sure the dog will come
Once my pups can come when called, ten out of ten times, then I explain not that close
At six to eight months of age, those teeth fall out, you'll survive, others have

I'm not in favor of control moves, pinning the dog, scruffing, must have never seen it done properly, I guess.
When pet owners do it, it seems to only make the situation worse

Puppies, I don't like electronics, but I will use throwing chains
Anyone....

This site deals with puppies and biting: http://www.canismajor.com/dog/bite2.html

And Ed sums up teaching 'no' right here:
http://www.leerburg.com/no-art.htm