If your puppy potties in the house, chews something he shouldn't or otherwise does something puppyish but not very cute, here's what you do:
*Put your puppy in a safe place.
*Get a good sized newspaper.
*Roll the paper up and hold it securely in your hand.
*Whack yourself in the head three times while repeating, "I will watch the puppy better!"
*Clean up the mess.
*Play with your puppy!
Training is the process of helping your puppy to form new habits --habits you want him to have. He's learning all the time, even when you don't think you're teaching him anything. If you allow him to do something you don't like, he learns he can. If you leave him loose in your house unsupervised before he's ready, he learns that he can chew things and potty in the house.
It's much easier and faster to prevent bad habits and teach good ones than it is to try to fix bad habits once they're formed.
Never, ever hit your puppy with anything - not your hand, a rolled-up newspaper, or anything else. There is no reason to hit your dog and it won't teach him anything you want him to learn. Some dogs respond to being hit with fear and become fearful of people. Some dogs become aggressive and will bite in self-defense. Either way, you will have created an unhappy and potentially dangerous dog.