Do not try to write your business plan in one sitting. As I mentioned in the beginning, for a traditional brick and mortar business, it could take in excess of 100 hours to compile all of the information needed into a comprehensive but yet understandable document. For online businesses, probably not that long. But your final product should be well thought out, well documented and easily understandable.
Explain the fundamentals of the proposed business: What will your product be? Who will your customers be? Who are the owners? What do you think the future holds for your business and your industry?
Understand gaps and weaknesses within the plan. Any casual viewer of the BBC programme, Dragons Den will be aware of how easy it is for weaknesses or gaps to be identified. Depending upon the purpose of the plan, this may, or may not, prove to be critical. It is often easier to recognise such weaknesses and gaps, and be prepared to deal with them, either by noting them in the plan itself, or having appropriate answers available should the need arise.