Funny how sometimes what sounds like good advice isn't. I was browsing online when I caught the alleged business plan tip shown here (although I added the red circle over it). It says you should write a "comprehensive, detailed business plan." And I say, probably not; only in special circumstances.
Instead, develop a streamlined, flexible, agile, lean, just-big-enough business plan and use it as the start of a forever-after business plan process.
Set a schedule to review it and revise it at least once a month. Understand that it becomes obsolete in weeks.
Keep it on your computer where you can refer to it easily and keep it up to date.
Focus on metrics, accountability, priorities, strategy, without a lot of text. For example, don't ever write text describing your company or management team in a plan that won't be read by anybody outside your company or your management team. That's a waste of time.
Of course you should know your business, your team, your strengths and weaknesses, and your market. That's absolutely essential. But do you take the business time to describe it in comprehensive detail, with edited text, statistics and formal research? No. Not unless you have to communicate it to outsiders. If you're jumping through hoops for a bank or investors, then maybe there's an underlying business value to the extra description.
But this kind of hype about big scary masters-thesis-weight business plans does a disservice to all the real business people out there who could use business planning to manage their business better -- set priorities, develop accountability, move forward strategically -- who unfortunately put off planning because of the mythology of the big formal document that feels as inviting as a high-school term paper.
It's business: Form follows function. If you don't know why you need a comprehensive, detailed business plan document then you probably don't. But don't let that off-putting tippery keep you from using business planning to manage your business better.