Core subjects to study if one wishes to start a new business?

Just a question…
What basic areas to study for if one needs to start a business. No degrees intended as I'm already at work but there are so many Uni's offering so much. What will be the core areas to study for.
Just a thought came to mind and found no similar questions. Thanks in advance to all answers.

Law
Finance
Human resource management
Organisational development
Marketing
Logistics
Business studies!