Now that you've got yourself figured out, it's time to figure out what kind of life you lead.
• Evaluate your living space. How much space do you have for a dog? Do you have a fenced yard? What kind of life do you lead? Do you want a great big dog, a little bitty dog or something in between? Sure, that Irish Wolfhound matches your eyes perfectly, but it's not gonna fit into your studio apartment. Conversely, that Chihuahua is never going to be able to navigate your 40acre spread. It seems obvious, but no matter how well your personality fits a particular breed, you have to make sure that your living arrangements match it too. It would be cruel to keep a big dog locked up all day in a tiny apartment.
• Evaluate your schedule. How much are you home? How many times per day can you walk a dog? If you just thought "per day?" then go back to chapter 1 and reread it ten times. Some dogs are more independent than others, so if you're not around a lot, it won't do you much good to get a clingy dog. Always remember that dogs get lonely, and if you're gone for days on end (even if the neighbor pops in just to feed it), the dog'll still get depressed.
• Anticipate future lifestyle changes. Do you have kids? Will you ever have kids? Are you sure? You don't want to get into a situation where you have to put the kid up for adoption because he or she can't get along with the dog. Better to get a kid-friendly dog in the first place, just in case.
• Evaluate your activity level. Picture your idea of a fun time, and be sure that the right kind of dog fits within it. If you love to go hiking, a Yorkie's not going to be able to keep up. If you like sitting and knitting, a Border Collie's going to make your life a living hell.
Once again, do your homework. Talk to friends, vets, dog breeders, and trainers to find out which breed is best for you.