For the brainstorming phase, when beginning to prepare a presentation, I do recommend to "go analogue" and get away from the computer. Thinking about your topic and how best to explain it feels a lot less like work when you're not sitting in front of a keyboard. You do need a way to jot down your thoughts, though.
A notebook is a good companion during the very early phase. Just write down what comes to mind. Don't worry about the order of things so much yet.
