Well, one thing you can do it hold a treat just out of reach of your dog. He might get a bit annoyed that your not letting him take the treat and bark, basically saying "Give me the treat please!" If you have a clicker, click it and give them the treat while saying "Speak" or "Bark". If you don't, just praise them and give them the treat, saying the same words! Oh, and by the way, don't do this too much, I recently was training my dog (whom was luckily a terrier) and got a nasty bite...to the bone, in other words, make sure you don't get your dog too upset. And another thing is that you don't treat them if they bark at someone outside, the dog will think that yapping his head off is good and will get confused if you tell him to stop barking, he will think it is good, yet bad, and won't do the trick out of fear of getting yelled at. Good luck with your training!