There is no way you must begin. I would suggest taking an introductory course or reading a book like "Heart and Hands" by Elizabeth Davis. Some midwives start by working as a doula. It really depends on what your life experience has been...
A new introductory workshop is being offered where you can explore midwifery and how it will work for you.
http://www.journeyintomidwifery.com/index.html