What preparatory steps should I be taking for admission into med school?
Speaking from (1) experience applying and talking to applications officers, and (2) knowing doctors who take part in the admissions process, I would suggest that the ideal medical student would appear as follows:


Any major, but very high grades in all pre-med courses
Very high MCAT score
Experience working in a hospital or medical research lab, with demonstrated results (good recommendations from doctors and published papers, respectively)
Very personable during the interview, well-liked by all interviewers


None of these should be a surprise; they just want awesome, academic students.