Training and intelligence
Yorkshire Terriers are intelligent, but it is up to you to persevere and use motivational training methods. House brekaing has a reputation for being difficult with Yorkies, but again it can depend on how much effort the owner puts in. Set your rules and be consistent.
Temperament
Yorkies are alert, brave and affectionate. They vary - some Yorkshire Terriers will be happy to be more of a lap dog, while most are more feisty.
Attitude towards strange dogs and people
They have very good ears, which alert them to anyone approaching their territory; they good watch dogs, and will in turn alert you. Good socialisation is important for Yorkshire Terriers to feel confident and relaxed enough to take the world in their dainty stride.
Grooming and shedding
Yorkshire Terriers do not shed. Their coats can grow very long, and need a lot of grooming. In pet dogs, it may well be easier to have the coat clipped.
Exercise
Yorkshire Terriers do like exercise, but don't expect them to do miles every day. Be aware and considerate of the health implications of a small dog - such as delicate knee joints.
Need for company
They do like company, and Yorkshire Terriers prefer to be with their people. Don't leave them for long periods if you want a happy dog.
General
This is a breed that has a long life span - you will be lucky enough to have your Yorkshire Terrier a long time, make sure they will be lucky to have you! They can be noisy, and have a tendency to feel the cold.