The way to prevent any condition developing is to identify and reduce the risk factors for that condition. The cause of clubfoot is not totally clear unless their is some underlying neurological disorder.
The more common type of clubfoot is called idiopathic clubfoot and the position of the foot when clubfoot is present at birth resembles a similar position of the foot in early fetal development. The thought is that there is something that halts the normal development from happening. This could be something like being exposed to environmental toxin early in the pregnancy, or smoking, or drinking alcohol or some other event.
This means that the best way to prevent a clubfoot is to follow all the standard advice that gives given when you become pregnant to allow for normal development to occur.