I've also had great luck with ignoring unwanted behaviors. When Cassie arrived here she literally jumped on us and mouthed (or play bit) our hands constantly and since she was 21 months old and 70# it could really hurt sometimes. We had to keep her in my hubby's office (he telecommutes & works from home full time) for the first week and only he and I worked with her at first until she settled down enough to be around the kids. We were just really loving but consistant. When she jumped up or play bit we'd say "no jump" or "no mouth" and turn our backs to her for 20 seconds or so. As soon as she settled down we'd turn back to her with pets, praise and sometimes treats. We also taught her to sit, down, etc. (with more treats
) and that really taught her to listen well, too. It worked great and very quickly. She came into the house a week or so later and we told the kids to do the same with her. She's been here now since mid Feb and you'd never know it'd been a problem at all. Your puppy is young and they're so smart and they really want to please, so he'll have it all figured out in no time.