I'm answering this specifically as a lifetime enthusiast and historian of the breed.
What nearly everyone here has said is correct. The GSD (of any color) is a breed that needs to be worked and have good firm guidance. This is a breed that will actively TEST your resolve and consistency (males will especially test), so all members of your family must understand that all training must be constant and consistent! The GSD is also a high energy and excessively smart breed and so its good to have a routine and a job for him to perform. That job can be anything from guarding the house, to Conformation (unless white in america), or even tracking! You can check any local training outlets in your area (not like petsmart or petco, but an organization dedicated to training) and they should have a variety of different classes you can take that specialize in different things (tracking, rally, obedience, agility) for your dog to do.
As a historical note. The idea that no 'reputable' breeder will have whites is absolute nonsense. I know American breeders who wouldnt touch the color white and they dont have the sense God gave a mule in regard to breeding. The correct idea should be that no reputable breeder would breed the GSD for anything other than to work (that includes you AKC show breeders).
In the 1930's when the breed was founded, the creator Max. V. Stephanitz actually did not like ANY solid colors, that included black. But he was also quoted as saying that no good dog is a bad color, and the grandsire of his chosen dog was actually a white dog. Capt. Stephanitz actually bred the first GSD (Horan or Horand) several times to other dogs and to his own offspring in order to solidify type. Needless to say, white was common and there were no issues with the color.
However, during WW2 after the breed had gotten significant noteriety in Germany, Hitler had members of the Nazi party infultrate the SV (The GSD club of Germany), and basically kick Capt. Stephanitz out of his own club! Confusing the white gene with the albino gene, the Nazi's/Hitler blamed all weakness of temperament and drive, and the dilution of colors to the White GSD. As a result, all white dogs that showed up in litters were culled or killed. We now know today what the albino gene is separate from white, as is the gene which dilutes color.
In the 1960's the USA adopted the German Standard, and unfortunately that included the erroneous disqualification of the color white. The few people who were enthusiasts of the white color, began to pick up and breed this variety separately. In many cases the drive today has been lost in the white dog, though there are a scarce few white sport dogs in existence. Today, the white GSD has evolved mostly side by side with the colored GSD, and by all rights is the same breed but lacking the serious drive of the main breed. Their basically all (sadly) transforming into AKC show dogs.
There is another false idea that white dogs arent good herders, because the sheep wont listen to a white dog the same color as them. However, this has been disproven in the Border Collie, as solid white or white faced dogs actively compete in herding. You also have to consider the fact that sheep come in brown, black, spotted etc etc, so to quote another breeder on the faulty idea of color effecting sheep herding, you would need a dog thats pink.
End of history lesson :3, good luck with your dog! Make sure though that the breeder you get from doesnt have just show dogs, and that she performs in at least 1 sport either agility, obedience, or preferably Schutzhund. Those breeders are the good ones :)!
over 20 years GSD research and study