Most likely you will choose a breed depending on your lifestyle and on your personal preference. However, the decision as to which breed is right for you should be made only after careful study and thought. Size, grooming, requirements, temperament, natural instincts, exercise needs and sex are just a few of the considerations involved in making the best selection for you and your family. An excellent reference source is the AKC website www.akc.org and the official publication of the American Kennel Club "The Complete Dog book". the book is updated periodically and is available at bookstores and from the public library.
Before you decide on a breed, attend a local dog show if at all possible, or visit a training class to observe puppies and adult dogs. Talk to local breeders. In short, do your homework. The right dog in the right family can ensure a wonderful relationship for many years to come.
No matter what breed you chose, it would be helpful to take your puppy through basic obedience training. Structured classes are available at reasonable rates.