Chilblains occur in the winter and are the result of an abnormal response of the micro-circulation to changes in temperature. They are not due to poor circulation as many people with good circulation can get them. They are also not really due to the cold, but are more due to when a cold foot is warmed up too quickly. It is the way that the circulation responds to this change in temperature that is the issue in chilblains.
To prevent chilblains, all you have to do is keep the foot warm, or if it does become cold, then make sure it warms up slowly.
If you get a chilblains, then use a cream and physical rubbing to stimulate the circulation and facilitate the removal of waste products.