Size. It is only fair to your puppy that it have adequate space in which to roam and run. For a small dog, an apartment is a much larger realm than for a large dog. Even though you will be taking it out for exercise, consider whether the home environment is suitable. Some breeds may also be more comfortable outdoors, and if this is the case you should only choose this type of dog if you have a yard.

Temperament. Different breeds have different tendencies in terms of personality, stress tolerance, and so on. A very needy, high strung animal is not the best choice if you also have small children, for example. On the other hand, neither is a more aggressive breed, so take into consideration the people that will be a part of the dog's life on a regular basis.

Activity level. All dogs need to be taken out for regular exercise, but some are more athletic than others. If you know you do not have the time, energy or inclination to really take your pet through their paces, choose a Chihuahua over a greyhound.

Purpose. Unless you are selecting a dog for breeding purposes, you may find that a mixed breed is more appropriate for you, as this frequently means a more even temperament, and in some cases, less likelihood of injury, as some purebloods are prone to joint problems and other disorders.

Your own personal preferences will play a large role in determining the right dog for you. Do you want a show dog, a highly intelligent dog that will learn amazing tricks, a good jogging companion, a watchdog, a hunting dog? It is important to choose a dog that you will enjoy spending time with, as this is going to be an integral factor in their happiness as well. Consider your main motivations in wanting a dog, and the types of activities you plan to pursue together.

Dogs are sensitive, intelligent animals, and make amazing companions. Do a little compatibility test on yourself and the types of dogs you are considering to ensure a good match. There is plenty of detailed information on dog breeds available online or at your library or bookstore. Do your research ahead of time in order to make a wise decision and choose a dog who will fit into your home and lifestyle, and look forward to many happy years together.