may i recommend you try and actually go observe an autopsy at either the hospital or your county medical examiner's facility? you'll get a much better understanding that way than to have someone explain it. for one, each autopsy is different because they're guided by clinical history. like living person medicine, your "differential" is guided by age, known medical conditions, the "history", and of course, the "physical exam". so a healthy 20 year old dropping dead is thought of much differently than a 66 year old man with a history of poorly controlled hypertension and dyslipidemia dropping dead.
contact your school's pathology course coordinator or department chair and simply ask to observe an autopsy - that's gonna be the best way to obtain the information you seem to want.