The first thing to teach is you to do all the things that people have to do with their dogs later in life and find impossible because they spent puppy time cooing rather than cleaning teeth, sticking fingers in paws, tails and bums. Taking pups to the vets, on car journeys, eating different foods, yarda, yarda, yarda.

Read all the "problem dog" threads and consider what could have been done when the dog was a pup to nip it in the bud?

Enjoy the pup months they pass quickly and the play time is teaching time - consider your pup like a project and document in an exercise book like an extended diary or car's log book/service history to record weight gain, illnesses (they happen) your dog's normal temperature (measured anally) pulse and breaths per minute. This way when the dog is ill you can tell the vet why with some meaningful data rather than a vague "...puppy ill..."

Food reactions, medicines given etc.

The first training mine had was being inspected on a table, just like is done at a vets. This was started as part-play and non invasive but now he will submit to inspection at any point of the day. When on a walk I will ask for the inspection and he will lay and allow me to poke and look at paws etc.

Waste of time? When your dog is injured by broken glass on the beach or a thorn on a country path you need your dog to be passive and under your control while you carry out first aid, the same is true if taken to the vets.

So if you get the dog used such a process as normal when it's important both you and your dog are not stressed because you're done it before many times. Seems an obvious thing to teach but I've seen spooked people at the vets with spooked dogs.

HTH