These articles may be of interest to you also:
http://www.yorkietalk.com/forums/pup...nt-stages.html
and
http://www.yorkietalk.com/forums/pup...rt-thread.html
May help you to know what to expect as they grow up. Many 'new' Yorkie owners get very frustrated with their babies, as they are very intelligent even as puppies, and will give you a 'run for your money'. My four are all smarter than me, I'm always trying to keep up with them! If they didn't love me so much I would really be in trouble! Lol...
One quick tip (or two): Not that you would, but a Yorkie should never be 'hit' or 'spanked' as a correction. Most totally will not understand this and will become fearful of the owner.
Best way to train a Yorkie is to lie in wait for them to do what you want, then praise the heck out of them and give them treats as a reward. (Positive reinforcement) So for say, potty training, take them to where you want them 'to go' and wait till they go, as they're 'going', repeat the command name (whatever you decide to call it... your choice: just be consistant) and when they finish, go crazy with the praise (clap hands, do a dance, say 'Good dog' with exuberance, and give them a treat.
What to watch out for: Once they learn this, many will feign having to go potty and get let out, and will squat like they're doing the deed, just to get a treat! Or they will come get you after having learned, so you can watch them 'go' and treat and praise them afterwards. Lol!
Ignore accidents... if they learn to get attention from the wrong behavior, you will begin to see more wrong behaviors.