The answers you received regarding business courses are correct. I'd also recommend you think through what kind of business you want to start, and take courses and intern in that industry so you have the subject matter expertise to excel. Good luck!
If you can, try to go ahead and get a business degree. Specific classes such as marketing, accounting, finance, contract law, Human Resources, and labor laws are all important. Some colleges offer entrepreneurship classes as well. My favorite was marketing analysis. Also look for classes that have project work. Those are very beneficial.
Any courses that will help you understand the business world. I would recommend business courses, accounting, economics, finances and personal finances. You will need to understand what it takes to live in the business world, analyze the current economy, understand supply and demand and know how to work your own books. Psychology courses may be good too to understand the consumer. There are courses that tie psychology with business for just that.