Method 5. Training an incompatible behaviour. A dog that has learned to sit instantly on request cant jump onto people. Similarly, being in a drop position is incompatible with barking.
Method 6 Put the behaviour on cue. Using reward based training it is easy to teach a dog to bark on cue. In the absence of the command the dog sees no point to barking.
Method 7. Shape the absence of unwanted behaviours. If the absence of barking, or being quiet, is frequently rewarded the dog will enjoy being quiet. Saying the words Quiet or Shush while the dog is not barking, as information, will auto-train the words so that the words soon become a meaningful & instantly obeyed instruction to be silent.
Method 8. Change the motivation and the need to bark is eliminated. Dogs that bark excessively are usually lonely, frightened, or bored!