Have a base in a well-rounded art FIRST. After you have a solid foundation, then you can think about branching out. Heck, depending on the art, and what it covers after black belt, you might not NEED to branch out.
Don't focus on the quantity of what you know, focus on the quality. Avoid being a mile wide and an inch deep in your knowledge.
Don't focus on the quantity of what you know, focus on the quality. Avoid being a mile wide and an inch deep in your knowledge.