A Business Plan is very important

The importance of a comprehensive, thoughtful business plan cannot be overemphasized.
Much hinges on it: outside funding from a credit institution, credit from suppliers, management of your operation and finances, promotion and marketing of your business.
Your business plan will also help with the ultimate achievement of your goals and objectives.

"The business plan is a necessity. If the person who wants to start a small business can't put a business plan together, he or she is in trouble," says Robert Krummer, Jr., chairman of First Business Bank in Los Angeles.

See: How to write a business plan .... made easy