I know right now you're thinking I'm nuts, because we all know one of the worst fears for dog owners is a dog that bites. But stick with me.
If you've ever spent any time around a litter of puppies, you'll notice that when they're not sleeping, they're playing. And what does that play involve? Biting - and lots of it. Puppies also tend to bite just about everything else they come in contact with. Mouths are to puppies what hands are to children. And just like kids who learn that there are things you should and shouldn't touch, puppies have to learn when and how to use their mouths. They need to do it before they grow up, too, when their jaws are strong enough to crack bones.
This is where it's really important to understand the difference between not biting and bite inhibition. Bite inhibition doesn't mean a dog won't bite. It means when the dog bites, it doesn't cause harm. Bite inhibition is why two dogs can get into a fight at a dog park and walk away with nothing more than a fresh dose of respect for each other's personal space. Because again, dogs hold the power to shatter bone with a single bite. If they wanted to tear each other apart, they could do it in a matter of seconds.
Thankfully those dogs don't want to harm each other, and they know how to avoid doing any real damage because they learned how to bite when they were puppies.
As puppies play, it gradually gets more and more rough until finally one yelps (because his sister bit him too hard) and play stops. He'll take a second to cool off, and she'll initiate play again and it will start over. You'll see this occur over and over with a litter of puppies, and every bite that elicits a yelp will be followed by a consequence (someone will stop the play session).
Assuming your puppy began his first 8 weeks of development living with his mom and siblings, he'll have some excellent foundations for bite inhibition when he comes home with you. So how can you keep that momentum going?
So glad you asked.
First, let him know that biting hurts, and will result in play ending. Yelp loudly if he bites, and when he stops to see why you stopped playing, start playing again.
Next, teach him about pressure. Mouthing your hands is fair play, but if he bites your hands too hard, or bites at any other part of your body, yelp and end play for a few moments.
Show him that there are times when mouthing is ok, and times when it's not. You'll want to give it a command, like "leave it" or "off". Tug toys and flirt poles are an excellent way to teach and reinforce this behavior. When you're ready to play, give him a command (like "take") and when it's time to stop, lure with food and reward when he drops it.
It's also important for teaching him that he can only bite and mouth when a person initiates it. You don't want your shepherd or staffy mouthing a stranger at the park just because they said hello.
Although not as pressing as getting your puppy socialized with people, you should find appropriate puppy classes so your puppy continues to learn bite inhibition with other dogs. You ideally want same age and multi-age groups, with various sizes and breeds. If you have a mastiff, you don't want his first interaction with a pug to be when he's 3 years old and full grown, because the bite and body inhibition he learned with his big dog friends isn't going to be appropriate for playing with a small dog.
Your puppy also needs to learn that while some dogs don't mind a lot of biting during play, others may not appreciate it.
For little dogs, they need to learn confidence around big dogs. Do not take your little dog to "small breed puppy classes" unless you're also enrolled in regular classes. If your little dog squeals and runs from an older dog, she's suddenly going to become a prey item.