Foundation

If you want power in your tai chi, begin with your lower body.
Without a firm foundation, power cannot be expressed through the framework.
Your feet must have three points of contact and the weight balanced equally between front and rear of each foot.

Move up to the pelvis.
The pelvis must be stable, with most of the work happening in the hip joint.

Now focus upon the torso.
It must be comfortably upright, without strain; lengthening from the hip to the crown.

Without these basic skeletal requirements in place, your structure will crumple if you deliver through it.