First and foremost a proper grip will assist with the wrist set/hinge.  The top hand must be placed on the club where the heel pad of the palm is set on top of the grip.  If the heel pad is not set on top of the grip the lead hand will slip and move during the golf swing.  You should also place the lead hand on the club so that there is a slight cupping of the lead wrist to assist with wrist hinge development.  A flat lead wrist will not allow the wrists to hinge correctly or enough during the backswing.

The trail hand (bottom) must create almost an air-tight seal between the tumb and forefinger.  If this seal is not set at address the golf club will have the tendency to slip or move during the swinging motion.

During the backswing the wrists should begin to hinge.  The motion is much like that of a hammering action.  The lead arm will remain extended to assist with swing width and the development of an "L"-shape between the lead arm and the club shaft during the backswing.  Once established the golf club will feel light during the backswing as opposed to heavy.

A great drill to begin to feel this sensation is the reverse hands drill where you hold the club cross-handed and keep the lead arm extended.  The goal is to allow the wrists to hinge up and move the clubhead up above the hands.