I am a careful pet owner. I won't get an animal unless I'm 100% sure I'm ready for it. They take up a lot of time early on and if you spend that time with them when they are young you end up with a great dog.
I can’t really speak for training the GSD as a puppy. I had one as a teen and he was a great dog, but he came to us as an adult. We lived out in the country, well off of any main road, and he had the run of the countryside. The farmers loved him because he hunted and killed groundhogs. He had a self-taught hunting method in tall grass that was amusing to watch, he’d start springing up over the top of the tall grass, boing boing boing, rapidly looking left and right the whole time. It flushed whatever he was after, and he could see it from above. Smart boy.
I can say that a male Lab puppy from a field bred line is going to be a hellion until he’s about three years old. They’re very eager to learn and very fixated upon their people, but they’ll retrieve or swim or go go go until they drop. Giving them a task, a job to do does wonders. You need at least a large enclosed back yard if not acreage, and if you don’t have surface water on your property a big, heavy duty baby pool will get used a great deal.
Best way (IMHO) is to go to a dog show and find the shepherd ring. Talk to the people there about what you want and they can point you to a good, reputable breeder. You want someone who is breeding for health first, then intelligence the rest comes with the package.
No matter what breed you are looking for, find those who love the breed first and they'll help you find your dog.