Advice for a first time dog Parent:
First off......Don't think you should buy a pure bred. Often, Unless you know a GREAT deal about the breeders, you will find they are poorly bred. Most Pure breeds have some genetic health problems that show up much more rarley in mixed bred dogs.
If you decide to get a dog, Go to the local resuce shelters (PAWS the Human Society, ASPCA, ext.) Wear nice comfy old clothing, and play with all the dogs.....find one you can't go home without. Thats how you find a dog.
I prefer big dogs, because they aren't as easy to step on (You may think that little poodle fallowing you around is cute, but wait till you are washing dishes one day and you go to back up and accidently step on the little critter)
You want to do a lot of research into training. And when you get your dog home, start out treating it like a puppy. even if the previous owners or the shelter told you he was house broken, go through all the steps anyway, remeber, its a new area, so they need to know what YOUR rules are.
If you are going to get a pure breed, make sure you research them too, check out what diseases or disorders are comon in the breed, and consider if you can handle it if those things happen to your dog.
And Please, PLEASE don't take other peoples predjudices in to accoutn, Rottwielers, Dobermans and PittBulls are NOT vicious dogs...training is everything, and my Pitbull mix would never hurt a fly, and she is huge....85 lbs.
If you want a dog that is highly trainable, look for dogs in the working breeds. This is because they are bred for inteligence. A lot of the toy breeds, or other breeds are bred purly for looks, and the breeders never took brains into account.
Thats all I can think of now, good luck, and I hope you can get a dog when you are ready.