German Shepherd puppy with biting issue

Hi we have a german shepherd puppy she is just over 9 weeks old and we are having a hard time with her biting and nipping. W have a tried a few of the recommended ways to stop her from doing this but nothing seems to work. We will replace our hands with a toy but she will 3 of 5 times try to bite our hand instead of the toy. We have also tried the thumb under the tongue method but that does nothing and making a high pitch yelp does absolutely nothing at all. If anyone has any advice or tips we would love to hear it, thank you!!

This is typical puppy play. Every puppy will do this. The best way to stop it is to get up and walk away for 2 minutes or so. You see, the puppy is wanting you to play with him and if you walk away he is not getting to play. You must do this IMMEDIATELY when his teeth touch your skin. Don't hesitate even for a second. He will soon learn that teeth on skin causes play to stop.

Hi Dee . My friend also has a severe biting problem with a kelpie a few weeks older. just tried the mouth idea with some success, waiting to hear back! he does the ignoring, the seperation, the growling, all work for a short time but he continues. Always has something in his mouth unless he is asleep! and it is usually a human! he is obedient in many ways except this and is very affectionate, but the biting is excessive. he is a 24/7 dog with his master and needs to go in car for gardening work etc. he is loves to be doing this but has an aversion to getting in the car, and again bites with More agression. he does not like to be in the sun in car ,so this may be why he resists, he is going to covering the windows. He is not taken in car on really hot days and has Air Con, but puppy has a mind set that he is going to be hot! so he resists to getting in everytime. looks like some sort of car training is also necessary... any suggestions for him.
Maybe socialisation with other dogs will help, as he has to be kept away for a few more weeks when needles are completed. he will spend much time on the beach after that, but so many unimmunised dogs around, not worth taking the risk. he comes from a brilliant breeder who does all the preperation for the owners, as I have the pups half sister, so definitely no problem there.
Please open for any more suggestions, as he is a special dog, i live accross the county so cant offer any hands on help.
I would enjoy the challenge with him, but my friend has much dog experience but not a lot of puppy raising experience.

thanks

What mouth idea? He is stopping the ignoring and/or walking away way too soon. THE DOG SHOULD NOT BE LEFT IN THE CAR!!! THE DOG IS SMART ENOUGH TO KNOW THIS. The owner is too dumb to listen. Even on mild days, it can get very hot inside a car if its in the sunshine durning the middle of the day. The dog does not need car training. The owner does. If the pup is immunized, the other dogs will have no health effect on him.

Quite a few dog owners have told me about when she bites to put your thumb on their tongue and press down and say a firm no... to make them stop biting. For Hurley is does and doesn't work it makes her stop but she she still does we replace our hands with toys. The puppy is teething and we've found the biting isn't as bad as it was before. as long as he is mouthing you with its front teeth your fine the breeder of hurley trains police dogs and said that you don't want them to bite you with their back teeth. As for the Car thing... you should never leave an animal in a car but if its taking it from one place to another.... it may be afraid of the car so take baby steps teach the puppy that the car is a safe place. We've both learned that it takes time and patience with our little one. And definitely take him to the dog park and socialize him!!!!!