An outline is not a cage; it is a map drawn before the hike. Its only job is to stop you from walking in circles for three months. That means it can be rough, incomplete and wrong in places — as long as it exists by the time you start chapter one.
Step one: write the premise as a single sentence with a character, a want and an obstacle. If the sentence needs a comma farm to make sense, the book does not know what it is yet. Step two: name the ending first. Not the twist — the emotional place your character arrives. Every act exists to make that landing feel earned.
Step three: build a three-act skeleton of no more than nine beats — opening, inciting incident, first threshold, midpoint reversal, all-is-lost moment, climax. Step four: turn each beat into a scene card with a goal, a conflict and a change. Stop there. Resist the urge to outline chapter seventeen in coloured detail; the discovery draft is where those scenes earn their keep.