Ah, the humble to-do list. When used badly, it becomes a source of stress and a trigger for procrastination. When used well, the to-do list can help you focus on what you need to do, when you need to do it.
There are a few ways to keep a to-do list. You can use pen and paper. You can run a command-line to-do list manager. Or, you can use a to-do list on your desktop.