I agree with anna_66--especially with a puppy, ignore or distract him from the bad behaviors and praise the good ones. Ignoring a puppy who's biting really does work wonders. The second he starts to bite, play time is over. And NILIF is one of the best things we learned at puppy kindergarten.

About using a squirt gun as punishment--I've read that you run the risk of making your dog afraid of water, and that can eventually be a problem when you need to give him a bath.
Has anyone else heard this? I'm not sure what I think about it, but it might be something to consider. In general, I'll admit I'm partial to positive rewards for good behavior (like teaching "release" by offering a really tempting treat)--but that's because I found those work best for my dog. I realize not all dogs are the same, though.

I do think that a really good thing to do is read a lot about different methods and approaches so you can make good decisions about what works best for your puppy.