Books on Methods
For an introduction to methods, there's actually a book about many methods. Change Journal is literally a buffet table for testing many methods to help you become more productive. Another really good book is The 1% Method where you get strategies for forming good habits and breaking bad ones! Through minimal changes. This is a book we truly recommend!
Returning to the topic of Bullet Journal, the book about the method is almost a must for anyone who really wants to dive deep into the method itself. Then there are also nice treats that instead focus on how to use your notebook. The book 101 Layouts for your Bullet Journal focuses on concrete spreads to create in your notebook.
The Bullet Journal method is based on organizing your life with paper and pen. This leads us to the range of writing supplies.
Books on Drawing & Writing
It's so much fun to try to develop your writing. Which has resulted in a bit of nerdiness. Drawing Fonts Creative Hand Lettering is a book we really recommend as it covers lots of fun things with fonts, drawing, doodling, and sketching. On the theme of combining writing/drawing, there is a really unique approach in the book Illuminated Letters Sketchbook.
Doodling and sketching. How fun is it to doodle out thoughts and ideas with simple figures? Sketchnote Journal is a book where you can easily learn to create visual notes. A really fun book.