Developing a solid business plan is critical to the success of your business. A business plan will help you determine how much money you need to start your business. Also, a lender or investor will want to review it to determine your eligibility for financing. Your plan should clearly outline how you plan to make money and include an estimate of your projected sales for the first year. Base your estimates on the size of your market, your competition, your price, marketing plan and trends in the industry. Also include in your plan your expected expenses for things such as supplies, rental space, salaries, insurance, etc.