01
The method, in order.
Warm or cool, and how strongly. Read through drapes rather than guessed from eye colour.
How much clarity and how much weight your colouring can carry before it starts wearing you.
The distance between your hair, skin and eyes, and how much a look needs to match it.
How a shade shifts against you as it moves through its range, which is where most guesses fall apart.
The season is the starting point. Refinement narrows it to the shades that genuinely work on you.
What it means in practice for clothing, makeup and hair, so the answer is usable rather than theoretical.