The most important thing for early puppies is exposure. They should be exposed to all manner of novelties. Tactile sensations such as flooring and uneven surfaces, handling and turning sideways and upside down. Heat and cold, noise and silence.
They should also learn how to hunt you for food and play. Teaching them what Yes means is critical to have them pay attention to you when it’s easy.
As pups mature they will increase distance from you and your Yes now proves itself worthwhile since you can Yes from a distance and they will come to you for food.
Far too many people bring their pups home and then try to teach them too much too fast. Those dogs that I see that where “puppy prodigies” are, by 12 months old, wrecked. Mentally flattened out. They have no resilience and even the skills they do well crumble at the slightest distraction.
Concentrate - particularly in the first 5months - of making as many experiences beneficial for your puppy.
Not everything needs to be fun, fearless and voluntary. If we maintain that paradigm, our dogs will become depressed, fearful and inflexible.
Since they have not been adequately exposed to frightening events such as loud noises, novel surfaces, manual handling, rough play, risk taking problem solving they have no mechanism to deal with the situation.
Instead they exhibit their breeding and their innate savage nature. Digging, howling, barking, lunging, biting, hiding, fighting, running, pacing, self harm, spinning. These happen, mostly because as a pup we did not concentrate on exposure to risk, teaching our predatory beasties to be exactly what they where born to be: productive savages in a civil world.