I highly recommend Rodrick's book: Making Kumihimo: Japanese Interlaced Braids - Hardcover (Sept. 1, 2004).
The pattern in Rodrick's book is a for a 2 levels braid. I started like that but it was tedious for me and very slow so I converted the design to a 1 level braid. The result is exactly the same, front and back, it is just a matter of linking some of the threads in key steps. Once I had the design ready it was much faster. I was able to make it work on one level because my takadai has 9-pegs komas so I had enough room for all the tamas.