I used to work in a grooming salon and we had long-haired dogs come in fairly regularly. Tyson was our one consistent GSD, an older guy who was a real dream with grooming even though hair fell off him in clouds if you so much as looked at him. Blow-drying him after the bath tended to get a LOT of hair out, but we did use a professional-caliber dryer. Human blow dryers generally aren't as efficient, I believe it's because dogs just have so much more hair. There's something like 60,000 follicles per square inch for dogs, compared to 100,000 total for humans, if I remember right.
After he was dried out, brushing him out took a while and we'd often have to do it a few times. He loved the attention, though, so apart from all the hair everywhere, I didn't really mind. For any long-haired dogs, I used a butter comb throughout the process for minor tangles, face hair, and sometimes longer tails or fringes. Start with the wider end, then fine-tune with the other side. It was also useful for combing out eye boogers that got stuck in the face hair, though do NOT stick a comb right up in your dog's eye to clean them. Use a paper towel, washcloth, or just your thumb.
First step with grooming proper was an undercoat rake, and sometimes a dematting rake if his coat was tangled up. Then I'd move on to a slicker brush, or same kind of rubber-tipped pin brush as you'd get at Wal-mart or wherever. Once I was starting to get less hair out with those, I'd use a Furminator to finish off the job. I would recommend a Furminator knockoff, used the real deal at the shop but have tried both and don't really see a difference.
Personally, I liked to use a butter comb afterwards as well, but that was just me. And, no matter how much brushing or how many brushes you have... lint roller. Buy grooming tools in person rather than online if you can. You'll get a better idea of which you like as an individual, which feel cheaper, and so on. Try asking a local groomer, he or she should be willing to answer questions and suggest types of brushes.