Advice for career

Hi guys I am currently working in big pharma as a Reg Affairs associate. In the past I worked in Process Chemistry for API production. Im interested in moving into Marketing/Sales either internally or externally in big pharma. I hold a BSc and MSc in scientific disciplines. Any advice on how to do this? Are there any courses/certifications I can get (I was planning to get an MBA after getting an entry level business position) Thanks all!