FIND OUT THE REASON WHY YOUR DOG BARKS
Find out what your dog gets from the barking and remove it.
Do not give your dog a chance to continue the barking behavior.
For example, if your dog barks when there is someone at the door, give him something to entertain himself with, such as a ball, or ask him to go to his bed.
Make sure your dog understands these cues before beginning this training.