I vote to get a mature dog from a shelter. Try the Houston Humane Society or the SPCA. Especially as a first time dog owner, dealing with a puppy is a ton of work. Older dogs are so much easier to care for and rescue dogs can make great pets. Both my dogs are rescues.
you need to get a 95-97 pound Doberman, preferably male, none of his claws removed, non-neutered, and def. not trained. here is where I got my Pinscher http://bigdobermans.com/index.htm friendly lil doggies. never cause no harm.