Purebred or Mutt:
Educate yourself on dog breeds and their temperaments. Some dogs are high-energy dogs and they want to run and jump and bark all the time. Some high strung dogs include: Chihuahuas, Dalmatians, Fox Terriers, and puppies are high energy. Other dogs such as Golden Retrievers, St. Bernards, and Basset Hounds are more laid back and easy going. You should know what kind of dog you would deal with the best. If you have children you need a dog that won't be aggressive and is very easy going. Toddlers who don't understand how dogs think will often torment the dogs, some dogs won't be bothered and others would try to bite the child.
Indoor or Outdoor:
This one is probably an easy choice for you to decide. If you are considering buying a puppy don't mistake their small size, because when they grow up they could be large. If you keep a puppy in your house when they are small it may be hard to send them outside to live once they are half your height and too big for your small living space. If you do send your beloved pet outside you will need to get them a doghouse and let them come inside when the weather is not favorable.