As you begin working on this type of project, chances are new ideas for threads will pop into you mind. Oh, what about this? It is easy to get distracted and start down a new path. But you also do not want to forget that great (or not so great) idea that just popped into your head.
Unless you develop your own strategy to handle these thoughts, one of two things is likely to happen. The first thing is that you switch gears and change topics in the middle of writing about the first thread.