Get a high school diploma or equivalent. This is not necessarily a requirement for medical school as much as it is for the college degree required for medical school admission. Graduating from high school is the first step toward becoming a physician.
Get good grades. While medical schools do not look at high school grade performance, getting good grades in high school will help you get into a good college that will better prepare you for medical school. Good grades may also help you win an academic scholarship. Because college and medical school are so expensive, scholarships may help you avoid hefty student loans.
Take the proper classes. Most pre-medical programs in college emphasize the sciences, specifically biology, chemistry and physics. Proficiency in math is also necessary. Position yourself so that the classes you take in high school mimic those you will take in college. This way the material will seem familiar to you and you will increase the chances of getting a good grade. Most high schools offer college preparatory courses, and some will even offer college credit for certain "college prep" courses. Medical college admission tests will have an essay section, so making sure you're proficient in grammar and spelling is important.
Get as much experience as you can volunteering in a hospital setting. Medical colleges look for well-rounded individuals, and volunteering will help with this. It will also help you get used to medical terminology and methods that will help further your medical career.
Many medical school admission boards look favorably upon being involved in research. While many research projects take place at the college level, research at the high school level is also looked upon favorably.