My Westies agression

Question
I've got a 1 yr old male Westie.  He's normally very sweet and very easily trained.  There is only one habit that I would like to break.  He makes aggressive noise and even bark when stranger approaches and wanting to pet him, and occasionally he shows his aggression to a family member who wants to pick him up and hold him.  Other than that he's a very lovely one.  How do I break this habit?

Answer
The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat.

You may also want to build trust in strangers by having them offer him treats.