You will usually need a relevant degree. A course that teaches both design and technical skills will give you the practical knowledge needed to work in the industry, so you should check the content of courses before making your choice.
You will need to put together a portfolio of work that you can take to course and job interviews. Your portfolio should include moodboards, designs and technical drawings.
It is also important to take along actual garments you have produced.
Because the industry is very competitive (more than 4,000 fashion and textiles students compete for just 500 jobs each year), any work experience you gain will give you an advantage when it comes to getting a job.
See the Can U Cut It? website for advice on finding work experience and more information about careers in the fashion industry.