Different breeds will have certain characteristics for which they were bred. Ask breeders at dog shows and look them up in breed books for further information. You must consider several things before deciding on a dog:
How much time can you spend with it?
Dogs are social creatures. They will not be happy left out alone. You must be committed to spending several hours a day with it.
What space can you provide for it?
If you live in a small apartment, you must take this into consideration: many dogs will not do well unless you spend a good deal of effort in meeting their needs. Don't be fooled by size into thinking a dog will be OK in a small apartment -- A terrier for example requires a lot of exercise. Conversely, many Mastiffs are content to-just lie on the floor and do nothing at all while you are gone.
How much money can you set aside for it?
Even if you get a dog from the shelter or otherwise inexpensively, you will have to buy food, pay for veterinary checkups, vaccinations and routine medical care over the lifetime of the dog. Not to mention replacing anything the dog may damage or destroy, or money for medical emergencies.
Do you have the financial resources for this? How much exercise can you give it?
If your time is limited, you should look for smaller or less active dogs that can obtain enough exercise in your home or from short walks. Note that not all small dogs are less active, or larger dogs more active.
How much training can you do?
Regardless of the dog you get, training will make your dog much more compatible with you and what you want to do. A trained dog can go to more places with you without disruption, and can be more easily a part of your life.
How much grooming can you do? How much hair are you prepared to have in your home?
You should give serious consideration to these factors: some dogs shed little and require no grooming (clipping, stripping, etc); others shed little but require more grooming; others shed but do not require grooming; and still others both shed and require grooming. Do note that just about all dogs will require some nail clipping regardless of conditions.
If you get a dog that requires regular grooming, are you prepared to pay for its grooming or learn to do it yourself and to do either regularly?
Which sex do you want, male or female?
There are pros and cons to either sex, all of which are generalities and may or may not apply to a specific dog. By all means, if you have a preference, get the sex you want. If you are not sure, it really doesn't matter.
What characteristics do you want in a dog?
Different breeds have been bred with specific purposes in mind. Dogs bred for scent, for racing, for retrieving, etc, will exhibit these traits. Consider which characteristics you would like and which will annoy you. Reading up on dogs in breed books (some are listed below) and talking to breeders will give you some idea of these kinds of characteristics. This also may be a reason to choose a purebred: characteristics in purebreds appear more reliably because of their consistent breeding. Do recognise, however, that dogs show individual personalities, and variety exists within each breed. Breeds are only a general indicator of what to expect.
Some questions to ask yourself:
What sort of exercise do I want to do with the dog? Walking? Jogging?
Do I want a dog that is bouncy and ready to go, or more relaxed?
Am I prepared for a dog with some protective tendencies? How about a dog with possible dog-aggression (because of its background or breed)?
Do I want an indiscriminately friendly dog or one that is more reserved?
Do I want a dog that must be near me whenever possible or do I prefer a more independent nature?
Will I want a dog that readily accepts other animals (e.g., cats, rabbits, etc.)?
Am I interested in: obedience, agility, hunting, herding, coursing, showing, etc. with this dog?
Mixed Breed or Pedigree?
While you can enjoy showing a dog with a good pedigree, in the show circuit, mixed breeds make equally loveable companions and are in-fact said to have more resistance to infections and they are freely available for adoption. But if you have decided on a breed, take the advice of people knowledgeable about the breed, choose a breeder whom you think is responsible and for heaven's sake don't buy the puppy just because it is available nearby or it is cheap!
Whatever the dog or puppy you choose to buy, please try not to buy them from "Puppy-Mills". In India, the sudden spurt in demand for puppies has led to a major problem - PUPPY THEFT. We at Close 2 Home Kennels have had personal experiences, and see the harrowing experience some others have gone through. One lady was even threatened by certain people. She tried to report the matter to higher authorities. So please try to get your puppy either from good homes, reliable owners and breeders, or adoption centres.