I tend to focus on tolerable behavior. When there is a payoff or reinforcer for desireable behavior, that behavior will be repeated. I've had puppies that are tender and quite sensative and if a stern "no" was used, they'd look crushed and kind of shrink back. I don't like to see that fear of me. I've also had tougher pups that aren't fazed by that and often they seem to think that attention must mean let the games begin. LOL. And they come after me with the vengence of a barracuda. Yelping works with some dogs and again, some think you're playing with them.
The thing is.....I ask myself, what is the puppy getting out of biting on me. He's trying to engage me in play or he's trying to make his teething gums feel better. So, if he's trying to get my attention and to get me to play with him....that is his motivation. So, by removing myself and ALL attention, he eventually learns that it doesn't work to bite hard. Dogs do what works. All the fun ends and his favorite person goes away. But, when he gently mouths me, I stay and pat him quietly....no rough stuff to get him all worked up. When I walk away, I hand him a Nyla bone or something first. "Here, chew this." And I'm gone. (of course not so much that I can't supervise him) I come back in just a minute and try again. The more times this is repeated, the higher the odds that he'll make a connection between mouthing gently and playtime, attention, affection continues... and biting anywhere near a painful bite ends all the good stuff. Not getting reinforced (consistantly) is enough to extinguish a behavior. That is why removing myself from his immediate area only should last for a minute or less and try again. Longer than that won't make any difference to him and his short attention span. He won't connect it anymore.
Anyhow, that link to that article is really good and has additional information...much, much more complete than what I describe.
But to reiterate...no matter what you're teaching your dog, if you can figure out what's in it for him....why is he doing this and then regulate that motivator....in the case of an unwanted behavior...remove it, prevent it, offer an incompatible alternative, reward for that behavior, make that behavior work for the dog. Give the dog a suitable outlet for his drives. There are all kinds of things you can do.
But if you think about it, there are soooooo many behaviors dogs do that we don't like...they don't fit human culture. And you can't go around saying, "no" for all of them or you end up shutting your dog down and he stops offering behviors in general (not conducive to learning). But, the list of what to do is shorter and therefore less complicated to teach. In other words, it's easier to teach a dog what works for him....what to do than what not to do. When he finds out what gives him a payoff and what doesn't, the choice will be his and he'll make the right one. LOL. He'll go for the behaviors which pay. And the others will extinguish when they don't pay. Just like us. A)Two jobs: You need money very badly. (your motivator) One pays and one doesn't. Does someone have to tell you not to take the job that doesn't pay? LOL. (but first you have to find out which one is the paying job and which one isn't, just like puppy has to find out which behavior pays and which doesn't) The only difference is that you probably can learn faster which job is the paying job. Puppies need lots of repititions, some more than others, extreme consistancy, good, immediate timing with rewards, patience etc since they don't have our culture or our language. Biting is absolutely normal to dogs. Now we're asking them to not do that normal behavior. They're making all the changes to suit our culture.
B) Puppy biting too hard: (motivation=attention, play, affection) All fun and attention ends, Mom goes away. (no pay) (Mom does give a nyla bone as an alternative for teething pain.) Puppy bites gently with a soft mouth. Fun, attention continues. Mom stays. (pay)
I always ramble too much.
