Like most physicians, we have developed our clinical skills by caring for patients, reading, discussing with other clinicians, and watching our mentors at work. Also, like most experienced clinicians, we rely on a relatively small number of basic rules repeatedly to guide our decisions in everyday practice. In fact, our daily clinical practice relies as much on this passed-down wisdom as on scientific data. These and other hard-won insights about the often-mysterious process of clinical decision making have traditionally been transmitted from physician to physician by example and via hallway conversation rather than via the written word. These rules are not meant to be definitive but have been put forward to encourage dialogue between clinicians about the process of clinical care and provide trainees with some useful guideposts in learning their way in the world of clinical practice.