All of the above advice sounds pretty good. One other thing that the trainer told me to do when I was having problems with Rosco. -When Rosco would do that, I would tend to coo, telling Rosco that it was ok and I would pet him. In my mind I thought I was reassuring him that the person is ok. The trainer told me that I was rewarding him for his behavior. She told me to snap his leash and tell him 'NO!' whenever he acted negatively towards a person.