Good dog training is all about building positive relationships where the dog has respect for it's owner and also where the dog realizes that the owner is the master and leader of the pack.
If the owner assumes the position of the leader of the pack and the dog knows and respects that position then it will feel more secure and be a happier pet.
Under no circumstances should the dog be fearful of it's master and that is why most current methods of dog training focus on the positive aspects of the dogs actions and reward it for the good actions that it takes rather than punishing it for anything that it does wrong.
A well trained dog that respects it's master will always want to please, and that leads to a better-behaved dog both at home and when socializing with other dogs and people.
These positive training techniques are also great at retraining dogs that have consistently done something wrong, as they will quickly learn that the rewards for good actions are far greater than the attention they are seeking from their negative actions.
Even older dogs can be trained quite well by using these methods so a dog is certainly never too old to learn new tricks.
One of the best resources available for both basic dog training and the correction of behavior problems in older dogs is Sit Stay Fetch: Dog Training Secrets to STOP Your Dog�s Behavior Problems!