The can of pennies worked for my sheltie (and they're notorious barkers). Take an empty soda can and put pennies in it. The INSTANT your dog barks, shake the can vigorously and say "NO BARK!" The sound is startling and your dog will not like it. Do it every time he barks. Eventually, he will learn that barking results in the penny can being shaken. You will also reach a point where simply saying "NO BARK!" will quiet him down. Good luck!