The following article has some great tips on making sure your dog is a well adjusted member of your family.

But when it comes to breed selection, I beg to differ on Sandy Bonifield's recommendations. We got our dog from the SPCA and he was an unwanted chow; nobody wanted to adopt him because they were fearful of his breed. But we knew from the SPCA's recommendation and from his pleasant demeanor that he would make an excellent pet, which he did. So, go ahead, get a dog from a shelter and find out what evaluations the shelter did... many dogs are abandoned for many reasons, and many times, these reasons reflect badly on the owner, not the dog...
Training dogs makes all the difference