Heinlein’s index cards
I keep with me at all times 3 x 5 file cards on which I make notes—at my bedside, in my bath, at my dining table, at my desk, and everywhere, and I invariably have them on my person whenever I am away from home, whether for fifteen minutes or six months. An idea for a story is jotted down on such a card and presently is filed under an appropriate category, in my desk. When enough notes have accumulated around an idea to cause me to think of it as an emergent story, I pull those cards out of category files, assign a working title, and give it a file separator with the working title written on the index. Thereafter, new notes are added to the bundle as they occur to me. At the present time I am filing notes under sixteen categories and under fifty-three working titles.
A story may remain germinating for days only, or for years—two of my current working titles are more than twenty years old. But once I start to write a story the first draft usually is completed in a fairly short time. Thereafter I spend time as necessary in cutting, revising, and polishing. Then the opus is smooth-typed and sent to market.
—Robert A. Heinlein, quoted in Robert A. Heinlein: In Dialogue With His Century
Alec Nevala-Lee 
An index card and a pen boots up instantly. Whenever I read a book first thing I do is stick a system card in as my bookmark. 3×5 in a paperback, 8×5 for a larger book. Thanks again for digging this up: Heinlein always looks effortless on the surface — the more one learns about writing, the rarer the ‘muse’ becomes and the more common the discipline.
Darren
February 28, 2016 at 4:30 pm
@Darren: I’d never heard them called “system cards” until now, and I kind of love it.
nevalalee
March 13, 2016 at 8:09 pm