Get a bachelors degree in a business discipline. People with masters degree in business have better chances of scoring such careers. It is best to do your majors in Human Resource Management, since it is the branch most closely associated with career counselling.
Practice human resource management on field. You will have to take up a job as a human resource manager, trainee or a general human resource job to build your portfolio.
Gain experience in the market. Ideally, you will need to have at least 5 to 10 years of working experience in the field to be credible enough to guide others.
Specialise in career coaching. You can either go for certifications or crash courses that allow you to specialize in career coaching. If you cannot go for such a certification, it is not a matter of life and death.
Get business exposure. You will need good understanding of all the major careers in your region. Before guiding others, you will have to understand how businesses work in your country.
Learn about behaviour in leadership and business. This can also be taken as a course during your bachelors degree. Most of your clients will ask you for ideas or pathways to their desired careers. You cannot guide them until you are aware of the psychological and behavioural aspects of people in the field.
Get on field experience in career counselling by joining a firm or agency that specialises in career coaching. This should be your first step towards becoming a career counsellor. Once you have enough experience in dealing with clients, you can then move onto your independent business.