For any organization, various functional plans-marketing, financial, human resources, production-have to be laid down, even though all the functional plans serve different purposes and all theses plans provide guidance and structure to the successful running of the business.
When I have received business plans, the very best responses come from people who have looked at the risks and have an answer for every question. What you never want is to throw a scenario at your plan and have to answer "I don't know what I would do in that situation". You want to plan for every possible contingency, and certainly all the major risks to the ongoing success of your business.
Have An Overall Vision : When writing your business plan it is really important to have an overriding vision of what your business is going to do, what it is going to be, and what you want to achieve. Very often it is tempting to get straight into the technical details, the monetary concerns, financial matters, where you will be sourcing supplies, etc. Now all these things will be vital in your business plan, but it has to be held together by a coherent, broader vision.
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?.