The personality of a dog is flexible and indeterminate. Dogs can be exuberant or shy; friendly or hostile; fearful or bold; aggressive or passive or some combination of the above. These differences in personality may to some extent be determined by breed, or individual genetics, but for the most part it is based on how and to what extent each particular dog has been socialized.
All dogs need to be exercised everyday in some form or fashion. The most common method is through the walk around the neighborhood, but is a short walk around the block enough exercise for your particular dog?
So you have made the decision to get a dog. Perhaps you had a bad experience once before with a dog who you thought was cute or friendly, but then when you got him home he turned out to be a holy terror, and the whole thing turned into a nightmare. Even if you have never had such a bad experience, the fact remains that choosing a pet is a life-changing decision, and it is one that takes a lot of thought and research.