Remember the proverbial expression 'not seeing the wood for the trees'? You need to see the 'wood' first, then delve in and start examining the individual 'trees', meaning the individual items which you will be breaking down later. So a great point is to make sure that you have that overarching vision _ and if you cannot find one, then maybe it is an indication that you are obsessing on a few technical aspects that do not necessarily make up a whole business as you had imagined it. A business that makes sense and is going to be sustainable in the future is one that has that clear vision within which all the smaller parts contribute to make it successful.
Organization and content of the business plan will evolve as it is prepared. For example, if the driving force of the plan is marketing or sales then a preponderance of the analysis and plan_of_action section will be more up_front and sales oriented in tone. With business plan's the world is your oyster; think from the center out to the edges and think outside of the box.