A dog with an aggressive attitude is one the most challenging of problems when you are facing correction training. There could be a number of reasons as to the cause of your dog's aggression problems, which can compound the challenge and the responsibility on your part. Before you do anything else, ensure your pet is fit and healthy. A vet can determine whether there could be a reason for bad behavior from a health point of view.
Once you are satisfied that his unpleasant nature is not due to a medical condition, you can then examine your options. There are really two routes open to you. Option number one is finding a specialist training centre where your animal will receive instruction, with or without your assistance or option number two is correcting the problems yourself with expert help.
Before you start any sort of training program for your aggressive dog, you should attempt to identify the problem, but of course this may not be possible if you do not know the dog's history. Usually the main trigger is dominance. Being pack animals, a dog's relationship is within the hierarchy of his "pack", meaning you and the other members of your family. Another factor is aggression stemming from fear and your pet could be rather negative towards other dogs or people. This could have arisen through neglect, mistreatment in the past or a single event which 'turned' him against certain things permanently.
The best way to tackle any aggressive dog training is to gain the dog's trust. A pet that trusts its owner will gradually moderate aggressive behavior. It is important to note that you are the pack leader, gaining trust does not mean letting your pet rule you in order to get better behavior. This can sometimes be counter productive and he will be far worse in his behavior towards others as he views you as his personal property. Always keep the overall perspective and your goals in mind.
You may find another issue you have is your ability to trust your pet again. If for instance, there has been an unpleasant incident involving your family or friends. If your dog has been trained by a specialist who assures you his aggressive nature has been 'corrected' you may still have a seed of doubt in your mind. This is normal and your wariness and caution will pass with your dog's continued good behavior. It is a good idea for an owner to be fully involved with the training of an aggressive dog, whereby you are witness to his progress and less likely to be over concerned about the past for very long.
For professional assistance in the matter of training your aggressive dog you can rely on the convenience of online training sites that have professional advisors who are skilled at dealing with any type of aggression. They will provide the expert knowledge which is the tool you must implement yourself. The importance of the owner being present whilst training comes from the fact that dogs learn by association. If for instance he is used to showing aggression when visitors come to the house, he will continue with this behavioral pattern. Consistently being there throughout is the key for training an aggressive dog, don't make similar mistakes over and over and never change your attitude towards him abruptly.
You can learn how to build a happy and loving relationship with your pet and enjoy each others company. He is man's best friend after all!