At the moment I am Mind Mapping my e-book.  I find the process very useful.  For the first time I am starting to have clarity about the structure of my e-book.  Mind mapping is an excellent way of structuring your thoughts.  A really useful software programme which I recommend you use is XMind.  You can download and start using the free version of XMind straight away and upgrade to the paid version later if you want.  The paid version has extra functionality however I am happily using the free version.  Please click on the following link to take you to the XMind site:  http://www.xmind.net/