Sorry to hear about your dog. I sure hope your GS mixed breed is good for you. We certainly love our purebred black with tan markings long haired German Shepherd. We get compliments on him everywhere we go and he is such a gentle giant (126 pounds) and is friends with anyone as long as they don't mess with Mama. We had 3 small breed dogs and while they were fine for lap dogs, they don't compare to our GS now for playing, guarding and companionship.
The first thing to do with a dog is to put up a good fence so they stay in and neighbors dogs stay out. Ours have 42 acres to run around in but mostly don't go too far from the house unless we go out in the UTV's to look at the far pastures. We put net wire fencing around the whole perimeter right after we got the place and it keeps out the varmints pretty well except for skunks, possums and armadillos (they dig under). My sister-in-laws' mixed breed GS loves to kill any possum he comes across (and skunk unfortunately).