When choosing a dog, it is important to ask yourself why you want the dog in the first place. Then decide if you have the room for it where you live as well as the funds to care for it. It is more than just food and an occassional walk. It is a commitment that will last for 15 years or more for most breeds. Research the breeds also: do you want a dog with short hair? long hair? size matters also. How much time do you have for it? A big dog needs room to grow compared to a little lap dog! Also, do research on breed dispositions. Does this dog breed as a whole enjoy people, or is it a one owner/one family dog?
Are there allergies in the family that need to be considered?
Once this is decided, visit area humane societies as well as breeders and ask questions. Read all you can and acquire knowledge on the various breeds available. Don't just settle for the first cute puppy that you see.
You have many years of happiness ahead of you. Make it worthwhile with a dog you will enjoy coming home to!