The best way to stop a dog from barking is to first create a relationship with him/her through training. Training teaches the dog to respect the handler so when s/he says “no” when the dog is barking, the dog listens and stops. Respect for the handler is developed by teaching foundation obedience skills to the dog. See the article which describes this process elsewhere on this website.
Critical during the first steps in this training is acquainting the dog with the consequence that comes with any undesirable behavior. This consequence is provided by the use of the command collar around the neck of the dog and the leash attached to this. So when an undesirable behavior occurs. the dog is given a snap on the leash which translates into a “bite” on his/her neck via the command collar. This is first taught during leash training when the dog is told not to pull on the leash. The dog then begins to understand that a snap on the leash and the discomfort to the dog that follows is a command to the dog to stop the pulling.
The same process can be used when the dog barks excessively. After initial brief training on the leash, excessive barking can be minimized/stopped by the same snap on the leash the trainer used to do the leash training. This may be all that’s needed. But it requires that the trainer/owner be willing to “catch the dog in the act” so the correction makes sense to the dog.
I have used this technique along with a muzzle for particularly stubborn dogs. In one case, I would correct the dog when she barked excessively as per the example above and then follow this with keeping her in a muzzle for about an hour to reinforce the initial leash correction. The caveat here is that in hot weather particularly, the muzzle should be used for only short periods of time and never left on the dog without supervision.
The Dogtra anti-bark collar is a great tool to use when you can’t be present to correct the dog. I use this at night when I’m in bed and don’t feel like running out to correct a barking canine. The collar works terrifically. Still I make it a point to first acquaint the dog with the neck corrections described above so s/he is prepared for the consequence s/he gets from the anti-bark collar for unwanted behavior.