I think that the first issue that we should discuss here is whether you should get a pet at all and if soo whether that should be a dog, cat, pocket pet (hamster, gerbil, guinea pig, etc.), fish, etc. There are lots of factors involved in that decision including who is in your household, activity level, how much time you can devote to your new friend, etc., etc.
After that decision is made then you can think about whether you want a specific breed of dog or cat (or other) or whether you should adopt a homeless pet from a shelter.
This article may help as well:http://www.homevet.com/petcare/select.html
There are *many* related issues so let's get started.