Nietzsche is generally quoted by confused people. He makes that process easy by being sometimes apparently vague or self-contradictory.
What is his highest principle? I'd point to two ends of his career:
(1) That we are manipulated by others altering our language and thus thoughts
(2) That our dour proleocracy says "No" to life, where we should say YES
These are the highest principles.
In the middle, he crusades against the loss of Aryan characteristics among Europeans, celebrates national tribes versus nation-states (the uninformed may confuse this "anti-nationalism" which is really "anti-patriotism" with a position against ethnic nationalism which did not occur) and suggests that Western Europeans cultivate the ancient races among themselves and not focus on the modern political divisions, which were post-French Revolution nation-state divisions.
He also loathed passive-aggression, which I consider the biggest problem in society today. It is the root of crowdism, conformity to illusion (note: regular conformity is fine), and a failure to act decisively.