Whether it is travel, study, cooking or any other activity involving a process, planning is usually the first step. The same holds true for business. Business plans are probably more important than the business itself. For example, the plan for a house is more important than the house itself, though it is the house that people remember and not the plan. But the house wouldn't stand without the plan, would it?.
I say that because of course you need to be careful with commercially sensitive ideas, as you do not want to pass your plan on to someone in the pub who then starts your idea before you across the road.
Describe the manufacturing or operating process and associated costs. Contain believable finical projections, with key data explained and documented.
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.