My gsd just turned 4 months old, and has the basic commands and skills down. (He learns unbelievably fast, but with that intelligence comes some "I'll do what I feel like" mentality--which needs fixing.)
Anyway, I'm looking now for some more serious training, preferably gsd-specific or similar. I'd be new to this but I find it all amazing and I can tell my pup wants it too. I'm located in central NJ so mostly anywhere in the state should work.