A business plan gives an outline of your business, the market in which it will operate and how it aims to make money - and should answer this question: why will your business succeed when so many others fail?
That does not mean you have to bust out Word and start the plan from scratch. A template is great--you probably are not doing anything that has not been done before, so it provides a proven structure for your plan. Pretty much everything on it can be customized.
Know your market. A big part of knowing whether your business will be successful is understanding your audience. Make sure your plan is clear about your target market – who will you be selling to and how many other companies are already selling similar products?
Do I Need a Simple or Detailed Plan? A corporate business plan for a large organization can be hundreds of pages long, but for a small business it is best to keep the plan as short and concise as possible, especially if you intend to submit it to bankers or investors — 25-30 pages should be sufficient unless you need to include photos of products, equipment, logos, business premises or site plans, etc. Potential money-lenders or investors will be looking for solid research and analysis in your plan rather than long, wordy descriptions.