If your dog starts to bite you when playing with them. Tell them in a firm way and wave your finger at them and tell them not to do that.
If they continue after telling them not to bite you then take there toy away if they're playing with a toy at the time and tell them to go lay down and if they continue start using a spray bottle with water in it.
When they start to bite you even just playfully take the spray bottle and squirt them with the water.
The dog will eventually realize that if they start to bite you they will get sprayed with the water bottle.