Great question! I say in order to become a successful entrepreneur you need to study the needs and wants of your consumers. Consumer behavior may not be a bad class to take. It helps you understand the minds of consumers and exactly what they are looking for when shopping. There is a whole science behind the mind of a consumer and the psychological aspect of it all is very interesting. Once you learn the needs and wants of consumers try to find a target audience in which your products will become appealing. If you really want to take it up a notch try to find something the current market is missing and how your product can benefit others. Once you sell the benefits of your product everything else will fall right into place. You also most certainly need some sort of sales and or management background.
You want to make certain you remain innovative and focus on the trends in the current market. Write down your over all vision for your business and always do a SWOT analysis (STRENGTHS WEAKNESS OPPORTUNITIES THREATS) of the market and your business. Focus on providing excellent customer service as well because at the end of the day they are the most important.