Planning is the first and the most crucial step for starting a business. Business Planning lays down step-by-step procedure by which would function. The various functional requirements of business-marketing, finance, human resource and production, provide information to all the concerned people like employees, venture capitalists, etc. and it also draws a read map to help the entrepreneur run the business successfully.
Have you done your research? Do you really know that the people you will be targeting want your product / service, and crucially do they want it AT THE PRICE that you will be offering it at? Whilst confidence in your plan is fantastic, you must make sure that it does not lead you down a blind alley along a path that is not desired by your target market. Don't assume what customers want, do your research and make sure that is clear from the start in your business plan.
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.
Obtain Feedback On Your Plan : When writing a business plan you sometimes end up locking yourself away. You might have unique ideas which lead you to seek some isolation and secrecy, or if you are going to be a sole trader you may only have one person to consult namely yourself. But it is fantastic to try and get broader input on your business plan - whether from a professional, or simply from friends and family whom you trust.