If you live in a little tiny apartment you should maybe not get a dog at all, let alone a giant dog, so you need to consider the size. Big dogs are generally more active, so they need more exercise. In addition they eat more. Little dogs tend to be yappy, but they are small, so you can often handle them better. We will go over these questions later.
Large dogs require a great deal more food than small dogs.
Some breeds are notorious for their drool. Some dogs don't drool at all. It is usually dogs with big, square muzzles that drool. I, myself, don't really mind the drool all that much, but I know their are those of you that get sick at the thought, so keep that in mind. Also you have to consider having a towel handy at all times to wipe the mouth, having drool everywhere in your house, and being prepared to get it on you at anytime.