Never use gloves when play fighting since a puppy will need to bite much harder before getting a reaction
Start any play fighting with a short training session so that they see it as a reward.
Frequently stop play fighting for short training interludes (say every 30 seconds).
Anything other than mouthing is not allowed and will result in the end of the play session.
Play mouthing must only start on command at the start of play sessions. It is not allowed at any other time and must not be initiated by your dog.
Only mouthing of hands is allowed (never clothing or other parts of the body)
Observation of puppies within a litter helps in our understanding of how they learn. Typically, they roll and scramble around and have simulated fights. Using their mouths to grab and bite each other is a common feature of this activity and of course itís not too long before one pup grabs and bites a little too hard. The natural reaction from the victim is a loud yelp, startling the culprit and causing a lapse in the play activity. Puppies soon learn that being too eager in their play-biting results in a scary noise and the momentary loss of a playmate, neither of which they like. This is how, during puppy social interaction, they teach each other to play gently.
Should I look to eliminate biting altogether
Not straight way. Biting is natural in all puppies and they must first learn mouth/jaw control and to inhibit the force of its bite. A world renowned animal behaviourist and vet, suggests a four step process to eliminate biting:
1. Inhibit the force of bites

As previously mentioned, puppies must understand that they must not bite hard. During this stage there should be no need for physical punishments or restraint. The best way to teach this is during normal play sessions with your puppy. If they bite too hard, let out a loud 'Ouch' and stop playing for a moment. Depending on how painful or severe the bite is further measures may include walking away from the play session or even leaving the room. Eventually your puppy will learn that painful biting results in the loss of its favourite human play mate.
2. Eliminate Jaw Pressure Entirely

Even though your puppy no longer hurts when biting, this step looks to completely eliminate bite pressure. This is achieved by gradually reducing the threshold that triggers the loud 'Ouch' to the point where even the slightest pressure results in a reaction. This form of biting is best described as 'mouthing' and you should look to achieve this by the time your puppy is 4-5 months old.
3. Inhibit the incidence of Mouthing

Now that the puppy mouths rather than bites, the next stage is to teach your puppy to stop mouthing when requested. A good way to do this is to hand feed a portion of your pup's dinner. Use the commands 'Off ' and 'Take it' to signal when your puppy can touch your hands to take the food. Practice this over time and you can gradually eliminate the food and use the commands during play sessions. Remember, this stage is about ensuring your puppy stops mouthing when requested, it is not about preventing your puppy from starting mouthing - that is the next and final stage.
4. Never start mouthing until requested

The final stage is to prevent unsolicited mouthing. Around the age of 5 months, your young dog should learn that it must not touch a person's body or clothes unless requested to do so, say during play fighting. Some trainers recommend avoiding play fighting altogether on the basis that, over time, many owners let play-mouthing get out of control. Dr. Dunbar suggests controlled play fighting is a healthy way to maintain the dogs 'soft mouth' so long as the play rules are obeyed at all times:
How do puppies learn bite inhibition