Puppy training/diet advice

Hello! I am getting a new German Shepherd puppy in about 4 weeks, he will be about 3 months old when I get him. I’d love any advice on how to start off training. I know a bit about German shepherds, I’ve had about 4/5 so far but this is my first German I’m raising on my own as a puppy! I’m very excited and want to learn as much as possible to be prepared for his arrival, thank you in advance!! 😊