This is a rule of general cleanliness -- if you shower starting from the top and work your way down, you’ll be the cleanest you can possibly be when you get out of the shower. Start by washing and conditioning your hair, wash your face, then work your way down your body, and end with your feet. Voila! No residue on your freshly-cleaned skin. This can prevent everything from breakouts (hair conditioner clogging the pores on your body and face) to keeping the soap you use from your feet far, far away from your face and body.