From fastcompany.com, the story of a simple to do list strategy from 1918, effective enough that it motivated Charles Schwab (at the time president of Bethlehem Steel) to reward an efficiency consultant named Ivy Lee $25,000 ($400k today) for improving the productivity of his executives:

The “Ivy Lee Method” is stupidly simple, and that’s partly why it’s so effective:

1. At the end of each workday, write down the six most important things you need to accomplish tomorrow. Do not write down more than six tasks.
2. Prioritize those six items in order of their true importance.
3. When you arrive tomorrow, concentrate only on the first task. Work until the first task is finished before moving on to the second task.
4. Approach the rest of your list in the same fashion. At the end of the day, move any unfinished items to a new list of six tasks for the following day.
5. Repeat this process every working day.

As James Clear points out, the real lessons are (1) use a method simple enough to actually work, (2) force yourself to make tough decisions, and (3) remove the friction of starting.

It’s worth reading the whole article.

Oh, and here’s another take on to-do lists from James Clear that’s worth reading:  Warren Buffet’s 25-5 prioritization method.