Starting a buisiness with a solid plan is an important step to achieving your dream. Why do you want to start a business? What product or service are you going to offer? Can you perform a service or make a product better or cheaper? Who will be your customers? How will you reach them, much less convince them to buy your product or service? Can you actually make a living doing this? These questions are just the tip of the iceberg in the thought experiment required to write a business plan that someone will invest in.
Below are some of the resources available which can help you in this journey.
SCORE - The Service Corporation of Retired Executives
Small Business Development Center - Angelina College
US Small Business Administration
IRS Small Business One Stop Resource