A lot of ski instructors will get you to focus on your hands, or upper body, especially if you are working on posture or balance.
However, to truly improve your skiing you need to focus need to be on your feet. Your feet connect you to the mountain through the inside edge of the downhill ski. Whilst, skiing your focus should be on feeling whats happening on your left edge and your right edge.
One of our favourite ski schools, 'Snoworks' based in Tignes in the Espace Killy, explains the concept in the video below 'Connect with the Mountain'.
Focus on Your Feet - Connect with the Mountain