The mistake many owners make when purchasing a Yorkshire terrier is thinking they are purchasing a low-energy lapdog. Telling your friends that you're adopting a "Yorkie," as they're often called, negates the most important part of their name: terrier. Like most other terriers, Yorkies need a lot of exercise and mental stimulation and can often be stubborn and mischievious. Thus, even though Yorkies are small dogs, they still require plenty of training.
Yorkshire terriers are a mix of several different terriers bred in Yorkshire to catch rats in clothing mills in the 19th century. Thus, they were owned largely by working-class individuals who needed a high-energy dog with an excellent prey drive. Though they rarely grow to larger than 7 lbs., they still have the energy of a rodent catcher and may use excess energy to remodel your house or yard (by chewing and digging, of course) if bored.
Before adopting a Yorkie, recognize that you aren't getting just a lap dog that will sleep all day. Yorkies need a lot of exercise and mental stimulation. A training program can help provide mental stimulation so begin to teach your dog boundaries, recall (come when called) and other tricks as soon as you bring it home. Yorkies also require a lot of grooming, including daily brushing if you are going to keep the long hair, so begin to teach it to tolerate grooming immediately. This can be done easily by brushing only a little and giving rewards. Keep the sessions short and build up to brushing the whole coat. Don't let the coat get matted, or grooming will become very difficult on you and your dog.
One major problem most Yorkie owners face is excessive barking. Yorkies are excellent guard dogs despite their small size, but an underexercised, undersocialized Yorkie can drive owners crazy barking at every noise. To avoid this, begins socializing your puppy as soon as you get it to everything you don't want it to fear: men, women, children, walkers and crutches, hats, beards, skateboards, bicycles and so on. Make this a positive experience with lots of treats. When your dog barks, say "quiet" and reward it when it listens. If not, put your dog in a quiet room for timeout and ignore it until it's quiet.
The other major problem facing Yorkie owners is potty training. Because Yorkies are small, they can hold their bladder for only an hour or less when they are puppies. Use a strict potty training regime by keeping a journal of when and how often your Yorkie relieves itself. When it is time, lead it outside (no carrying) through the door you want it to use. If your dog goes, give it a treat and let it back in the house for free time. If not, put your Yorkie in its crate until its next bathroom break. If your dog can hold it for an hour, repeat in an hour. Continue this until there are no accidents.
Training with Children
Many Yorkie breeders caution that Yorkies should not be placed in a house with small children, because they are so fragile and easy to injure. If you adopt a Yorkie and have children, don't allow any roughhousing. Teach your children how to politely interact with the dog and always supervise any interactions. Teach your Yorkie to be calm around your children as well by keeping it on a leash and using timeouts if its behavior gets too excitable. Remember to give lots of additional exercise if using timeouts frequently.