well layla never barked.. but since being on vacation.. shes taken it up as a hobby! we try a few things... first... squirt bottle with water... i carry it around and squirt it on her face when she barks.... when that doesn't stop her i grab her nose and hold it and say "ah ah" in a stern tone. when THAT doesn't work i grab her and turn her on her back (to tell her i am in control) and say no barking... but i think i've only had to go this far about once.. she usually stop with the water.. it REALLY pisses her off
HOWEVER yorkies are known for being "watch dogs" not guarddogs, but watch dogs... so it is hard to get her to stop when someone is at the door... i let her bark.. but it doens't go on for long.... she can alert us but that's it. good luck... it's a tough one!