I mentioned the financial aspect of a plan earlier, so let me add this. Another fact about financials to consider: not all business activities are about making money. Point being, in most enterprises financial considerations are centric to the document. But there are some other considerations. For example, a few years ago I wrote a plan for a new subsidiary that was focused on developing an inventory of patents. The potential financial returns were years into the future. Those patents may or may not ever have commercial value. Another example is a non_profit enterprise that has need for a complete roadmap for growing their profile in a market, of which a marketing plan would be the centerpiece.
If you're one of the many people thinking about starting a small business, having a business plan is one of the first things you should have on your list of things to do. It doesn't matter if you're starting a small business from home or away, having a plan for your business is considered a blue print for a successful small business. What is a business plan and why do you need one?