Need to make small steps and then have a second revision, and a third. Like programming, when I have an idea for a project I just make it work first, to see how to make it better, add some details, and when it is at a functional point I rewrite it and that second revision is much nicer.
The same with writing a book. If you try to do it all at once you get overwhelmed and lose interest. Get the first draught done and then start working on the second.