Biggest initial mistake I made was assuming my normal daily activity especially sleep patterns would remain intact. I also was taught the virtue of patience via the pups I've had over my life as I would not consider myself a champion at patience...however I am much more patient today thanks to the pups.
I also would have better served my first pups by being a bit more protective in the beginning months...not to say I should have isolated them from the world but more along the lines that I should have been more aware of any potentially negative situations that could arise during this important time period in a dog's life. Going forward with each new pup I've had over the decades has taught me that it is much easier to indoctrinate a pup with a very discerning and alert "eye" rather than having to deal with any negative situations during this developmental stage.
Even though I was aware that GSD pups require a bit more "effort" and patience than other breeds, I was somewhat surprised how often my patience was tried by these lovable little fur balls replete with needle-like teeth.
The fact that you are doing your DD and asking questions would indicate that you are well on your way to providing wonderfully for a new GSD pup. Believe me, the effort you put into raising a GSD properly is so well worth it as you will have the most incredible furry companion you could wish for. Keep us posted when your new pup arrives and the journey begins.