Having a well-trained and behaved dog can mean the world, especially if you are out a lot and have to deal with other people and dogs on a daily basis. If it is the case that your pet doesn't know how to follow orders, than you will have not only problems, but also a smaller connection with it. So make sure to have your dog trained, or to do it yourself, since it is not that hard and you can find information about it all over the internet. The easiest orders, even if your canine follows them, should also be trained, just to make sure it actually understands them.
When speaking of a Yorkshire terrier and training, there is not much to be said. These dogs won't make any insane things, but they will be able to follow any not too complicated commands. But whatever the breed characteristics tells you, you will be able to achieve even high standards if you are devoted and if you transfer that devotion to your pet. A special thing with training and the Yorkshire terrier is that they need devotion and a little more time to get it than some other dogs, but they can do it if you are willing to help them.
Quite a nice thing is that Yorkshire terriers are playful. They also have more energy than you would imagine. But all of this adds another layer of weight to the training, so make sure there are no toys around you and that you both had a hard exercise before you start. The ordinary commands like sit, come and stay are generally easy to learn, but a Yorkshire terrier will need time to master them, mainly because of their playfulness and their amount of energy. But one uplifting thing is that you will find it easier to train the harder commands since they require full attention and offer even tastier snacks and rewards.