Reddit mentions of Medical Sciences

I would start with textbooks then move to reviews then to original research (but you probably won't get that far until actually in the job.)

Perhaps go by system if you want and look at the relevant basic sciences (anatomy/physiology/biochem/pharm etc), clinical medicine/surgery and then clinical skills (history taking/examination/procedural skills etc) for the major systems eg CVS, resp, endo, GI, gen surgery, neuro. I've linked an example textbook I used.

It's pretty tough to teach yourself the material to be honest so focus on the patient not the underlying science, go through cases (such as those featured in NEJM) to get a picture of the ambiguity involved in medicine. Visit websites such as almostadoctor, handwrittentutorials, trickcyclists, geekymedics123, DoctorNajeeb, teachmeanatomy, become familiar with the language and the feel of medicine as well as establishing some knowledge foundations. It's knowledge, skills and attitude that make a professional not just knowledge.