You can use pen and paper, index cards, a text file, a dictaphone, a Word document or mind-mapping software. This is never a bad thing. It turns out that what works best for me is following some advice I got while I was still in college.
We become lost in the details, and somehow all our worrisome thoughts fall away. The first time you do anything is the most difficult, and writing a book is no different.
The formula comes down to being engaged with the material, keeping your mind alert, and actively trying to figure out what the book really means. Do I have to finish my book in a week?
Repurpose it again for a workshop.
The key is to have a system. If you are wondering how you can possibly write an entire book in a week let me start by saying that while this method lends itself best to nonfiction books, it can be easily used for the crafting of novellas. Find a quiet place to sit with a pad of paper and a pencil.
It can go from there but you get the idea.
The full program includes access to all 6 modules of the full Write a Book in a Week program.