@ Shibby - Dogs need different nourishments, But they usually eat any kind of food, some do not eat raw foods, though. German Sheperds are among those who eat any sort of food, I try to feed him what I myself eat and rice is good for them.
The best way of starting keeping a dog is to get your desired pet as a puppy and then raise and train him/her as your will, specially those enormous breeds and other breeds with higher violence such as doberman. They are great guardian dogs literally but need to be trained greatly, otherwise will cause some problems for the owner. I myself am an amateur and prefer to start training breeds like German Sheperd. Rottweilers are loyal as well but not as much as German Sheperds.