Another point of contention is how optimistic you should make your business plan. The problem with making over-optimistic predictions and plans is that these plans could well go wrong. Unforeseen circumstances can always put a spanner in the works. Therefore, it's wise to err on the side of caution when it comes to devising your business plan. Indeed, it's wise to predict conservatively and prudently when it comes to assessing the possibilities of future targets, sales and profits. A worst-case scenario will always prove to be less of a shock than one that raises expectations too high.
You may find that the easiest part is the actual writing of the plan. The real work comes in the data-gathering, which may take you a hundred hours or more, depending on what you already know or have researched. If your new venture is in an area where you've been working, you may already know about your customers, your suppliers, your marketing plan, your organizational structure, your financial and cash flow needs, equipment, inventory, and so on. If you know all of these except for Marketing, say, then this is where you will need to invest some time and effort. You can find a wealth of information by utilizing the traditional data sources such as chambers of commerce, major cities' websites, trade associations, the US Census Bureau, trade journals, magazine and online articles and advertising, etc.