An internship is valuable and may be required.

Take courses in non-business subjects. Good skills in writing, speaking, and critical thinking are needed for advancement in the business world. Also, fashion is part of the general culture. You need an understanding of the arts and social forces to understand trends in fashion.

Some business courses in high school can be useful preparation for a career in this field. However, you should take only a few, especially if you intend to get a bachelor's degree in this field.