Your Dog's Temperament
Your dogs temperament should match yours. Don't choose a breed that is highly energetic if you're a couch potato. On the other hand, if you want a dog that will follow you everywhere around the house and who is always ready for a game of fetch or tug of war then you should consider a dog that is highly active and always has a lot of energy, instead of one of the lethargic breeds.
Tiny, Small, Medium, Large or... Giant
You don't have to have own a large house to own a large dog (although a tiny apartment isn't going to be big enough for one of the giant breeds). If you can take him outside for a good hour of two of exercise every day... a large dog can live in a small house or apartment just fine.
Keep in mind that large dogs are more expensive to keep. They eat more food, which costs you more money. Tick and flea preventives cost more for large dogs, as do other mediations.
When large dogs eliminate, they eliminate a lot more than small dogs. More goes in and more comes out of large breeds. Which is something to keep in mind if your dog will live inside - especially if you live in a high rise apartment and he will have to be litter box trained (there's always going to be more to clean up).
Read the rest of the article at www.justjustdogbreeds.com.