Getting a pet and especially a dog is not a trivial decision. While I am not an expert I have owned dogs all my life. First you have to ask yourself what you expect out of the dog? Will the dog be allowed on the furniture? the bed? allowed to sleep with the family or sequestered in a seperate room?
Then you have to ask yourself what kind of temperment you think you could deal with. For example Border Collies will not do very well if their owners cannot spend lots and lots of time with them. The same goes for australian shepards. These breeds (my favorite) demand lots of attention and excercise....I would not reccomend them for first time dog owners. It sounds like you want to get a rescue pup and I have owned several over the years. Realize that in getting the dog from the pound it might be sick and require vet care since the pound has all manner of illnesses present. If its a pup you decide on they will probably require some type of neutering or spayin proceedure performed usually at nominal (but not none) cost.
Don't expect the dog to come with all the good manners you want be prepared to be very patient. Do a quick internet search for picking a pup or dog to see how to quickly judge a dogs temperment; i.e. dominant and maybe not a good choice versus docile and maybe the perfect new famiy member. Also remeber that dogs respond best to gentle persuassion and love to be rewarded and praised. You should never have to strike your dog!!! I would suggest you look into some books on clicker training and positive reenforcement training. Do you have a yard or live in an apartment would also dictate what size dog you might want to consider. Heck if you have a yard you might want to try agility training which is by far the best fun you and your dog will ever have together!!!!
sorry for the rambling nature of the post....any questions ask!