My little 8 week staffie pup Alfie is exactly the same, especially when he is in full on play mode! I always try to have a toy in hand to divert him. When he starts nipping at feet and hands too much I yelp and ignore him for a few minutes! When he licks nicely he gets heaps of praise. My motto is, ignore bad behaviour and reward good! It is still very early days with Alfie, and if I remember rightly, when my labradors were pups, it takes a few weeks of consistant positive reinforcement, but they do get there in the end. Hope this is of some help...

Jackie