Finally, a grooming sticky! YAY! I can put all my grooming spiels down for posterity.
The best tools for grooming a GSD are a soft slicker, a firm slicker for the thicker areas, undercoat rakes (for longcoats), Zoomgroom or rubber curry comb, and a shedding blade or Furminator.
The thing to remember with the Furminator is to use a light touch, like you are just petting the dog with it. You don't need to use a lot of pressure; keep your wrist relaxed and just let the tool do the work. Don't go over one spot for too long, and be extra careful over any bony areas. 5-10 minutes of Furminating once or twice a week is plenty. If you over-furminate, you may end up with bald spots or skin irritation. You definitely can remove more hair than you mean to if you aren't careful!
You will hear people say that the Furminator "ruins" the coat. This is not true if you use it properly. I'm a professional groomer, and I use the Furminator all the time with NO coat damage whatsoever. It is not designed to cut hair, only to grab the loose hairs while allowing the live hair to slide through undamaged.
CARE OF LONGCOAT GSDs:
Coaties *seem* not to shed as much, because the undercoat that dies tends to get stuck in the longer hairs, and sits there. This means a coatie needs MORE brushing than a short coat; even though they seem to shed less, that coat will quickly become tangled and matted with the dead undercoat stuck in it. If you bathe your coatie at home, make sure you brush and comb through the coat all the way down to the skin both before and after bathing.
HIGH-VELOCITY FORCE DRYERS
This the best "brush" you can ever use on a GSD. A high-velocity "force" dryer is simply a very powerful blow dryer that blasts out high-pressure, room-temperature air (not heat). Use it after the bath to dry the dog from the root of the hair to the tip, or use it on a dry dog to blast out dead hair, dust and debris. An HV dryer will cut down on brushing by about 90%.
The little orange Metro dryers are about $140, on up to the K9III, the most powerful dryer available to consumers at around $400. Buy the most powerful dryer you can afford, and you'll never regret it.
GETTING YOUR DOG USED TO THE HV DRYER
First thing you need to do is tie her to something sturdy so she can't run away. Don't let her get into the habit of bolting every time something scares her. Then, put cotton in her ears.
Then, turn the dryer on the lowest setting and let her get used to the sound of it. While the dryer is running, scratch her rump, right above the tail, this is a "magic spot" for dogs and should calm her down.
Once she's calm, replace the scratching hand with the dryer nozzle, making the same scratching motion with it. If she spooks, just go back to scratching her rump. But be persistent, and don't give up, no matter what she does, or she will learn that she can get her way by acting up. Eventually, she will begin to notice that the dryer doesn't hurt, and in fact feels good.
Once she calms down and allows you to blow air on her rump, give her lots of praise and encouragement, perhaps a high-value treat, and slowly, gradually, work your way down her rear legs, then up her back. Don't go anywhere near her head yet. Work your way around to her sides and underside, then that "magic spot" on her chest, between her front legs, where dogs love to be scratched. Slowly, gradually, work your way up toward the neck, avoiding the ears. You may be able to dry her head a little, or you may not for the first time. If at any point she starts to freak out, move the nozzle back to one of the "magic spots" on the rump or the chest. Keep going until she is at least 90% dry.
I have not yet met the dog that hasn't learned to tolerate the blow dryer when this method is used. In fact, most big dogs realize that the dryer feels good, like a massage, and many will lean into it. I have a lot of big dogs who LOVE to have their necks blowdried, right behind the ear, and will stretch out their neck for me. Most of my big dogs willingly jump on my drying table when it's time for the blow dryer, in fact sometimes when I want them to get into the tub, they'll keep trying to jump on the drying table.
When you're all done, give her a high-value treat and lots of praise. Eventually she will learn that grooming time is a rewarding experience and she will look forward to it.