I use an idea web first. I start with an empty circle representing the title, then orbiting circles for major sections of what I am writing about. Around those, I start adding details, and so on until I have my paper almost completely written in front of me. When I have an assignment where I need to turn in an outline, I simply transcribe the web into that form. Each orbit is a level in the outline.
No matter the size of the paper, 4 orbits is enough to sketch down to individual sentences.
For small papers, 3 is enough.