Make it enthusiastic, professional, complete, and concise. If you are applying for a loan, state clearly how much you need and be precise in how you are going to use it. Also include detail about how the money will make your business more profitable, thereby ensuring repayment of the loan.
If an online business, you need to go into detail how you will attract customers to your website. General statements like "I will use Face Book ads and email marketing" will contribute almost nothing to helping your cause unless you have detailed statistical analysis of tests you have conducted or of another similar business you have been associated with. If you do not have any data upon which you reference your estimates, it could show lack of proper thought to the remainder of your business plan.
You may not have thought much about your competition or outsourcing some of your work, but things like that will impact your ability to make a profit. And you will find this especially so in the beginning phases of your business. Even you are just opening a lemonade stand in the front yard, you will still need to know what Susie is selling her lemonade for on the next street over!
The next section, themarketing plan, gets into the details of what your business offers and what market it serves. Marketing is the communication of how your products and services "ease customer pain." Show the problem and how your business solves it. Marketing is a necessity for every business because once your doors are open, you must invite customers to come in. Everything you do in your business that affects customers is marketing because it sends a message about your company.