A puppy under 16 weeks is the equivalent of a toddler.  This playful nipping and chewing should be handled differently than that of an older pup.  Nipping and chewing from a puppy at this age is telling you he needs something.  Perhaps potty, food, or water.  Rule out these needs before you proceed to punishment.

Puppies older than 16 weeks now are moving into a different stage, they're teething and very susceptable to learning bad habits.  Teething is an important factor to consider as puppies will teeth till they're about 6 months old.  In order to sooth his aching gums he chews.  To facilitate his need we must give him the right things to chew on as this can also begin a bad habit of chewing on inappropriate items, such as: your furniture, shoes, carpet, etc.

To you as an adult this mouthing, nipping and chewing may not be that bad, cute even.  But, we must nip this habit now because we do not want it to carry over to a child.  Here are some How To Stop Puppy Nipping, Biting, and Chewing Tips.

1. First and foremost, BE CONSISTANT WITH YOUR COMMANDS.  Always tell your puppy "NO, (name)" very firmly. 
2. Always praise your puppy for kisses and good loving.
3. The quickest and most effective tip I've found for a nipping, biting or chewing pup is to ignore them when "No" doesn't work.  First cry out in pain, but do not remove your hand (removing your hand incourages the puppy to continue), if it proceeds after doing this say, twice, yelp in pain and turn your back to your puppy, when he continues to try to play, get up and leave the room.  The reasoning to this tip is simple:  The puppy played rough and you won't stand for it.   A few times of this and your puppy will learn "If I'm rough, my playmate goes away."
4. Another effective method is interactive play with a toy instead of your hands.  Ropes and squeakies are good to put between you and the pup.  If the pup goes for you instead of the toy remember #3.
5. One other effective method I've found is using a product called "Bitter Apple", it has a very unpleasant taste and spraying this on your hands before playtime can eleviate the painful play.

These are methods of what to do for a puppy chewing, nipping and biting you.  But what do you do when it's your material possessions that catch his attention and relieve his frustrations and boredom.  Visit: Destructive Chewing in Puppies and Dogs to learn how to keep your puppy from chewing up your stuff.