Buy shoes of the right size. Apart from the size, you have to ensure that the length of heels that you are buying, does not de-stabilize you. One should buy shoes in the afternoon or evening when the feet are swollen from the days walking.  

Exercise
Sit comfortably on an erect chair and clench your toes, then relax them –do this 4-6 times a day. This exercises your ankles, keeping them supple and lean.
Bathe your feet daily. Take a basin of warm water to which a little salt has been added. Soak your feet in this. Your aching feet will get instant relief.
Giving them a pedicure are the very basic necessities that go a long way in ensuring that your feet remain soft, shapely and supple.