Here are three of your first lessons I shall be mentoring you about; listen well, my thickheaded nephew.
1: to eat everything, kill everything, hoard everything (not necessarily in that order).
2: start on a strict diet of meat, preferably fresh cow or sheep (and always chew on their larger bones, for good strong gums).
3: a few of the better techniques teaching exactly how to squash a knight’s head.
4: to learn the basic lesson of any dragon of a young, and powerful age. Not to uselessly blow fire at the attacking knight, who will only block it, but pretend to do exactly that, so the idiotic human will raise its shield in protection. Then promptly squash him flat into the ground, then if you're hungry, you can store him for pancakes later.
That is enough for now; I will soon be sending more of my amasing and well-spelled letters that will soon have an aura of learning and terror.
Your ferocious, incredible, fearful, terrible, and most modest uncle