For stability, you must balance your weight over the downhill (outside) ski. To force your weight onto the downhill ski, your body must move laterally: drive your outside knee into the hill and lean out over the downhill ski with your upper body.
There are six movements that will help you achieve this.
1. Angulate the downhill knee. Consciously push your outside knee toward the hill. When pushing your knee in, your upper body must lean out to balance. Otherwise, you would fall over. This allows you to balance on the downhill ski. If you angulate both knees, your weight will be forced onto both skis rather than just the downhill ski.
2. Keep the downhill ski under your body. If your body is over the downhill ski, your weight will automatically be over it.
3. Balance on the inside of the downhill ski. Picture the inside edge of the downhill ski as a tightrope on which you are balancing. If you are poised over that edge, your weight must be distributed over the downhill ski.
4. Drive your outside arm to the outside. Forcing the outside arm out to the side and away from your body puts your upper body over the downhill ski.
5. Lift your inside arm. When you lift the inside arm, your upper body will lean to the outside of the turn. Your weight will be balanced over the downhill ski.
6. Keep your outside shoulder over the downhill ski. Pretend there is a dot on each of your shoulders. As you turn, place the dot of the outside shoulder over the downhill ski. If the shoulder is over the ski, your weight must also be over it.
As you practice, concentrate on one movement at a time. Remember, all six movements lead to the same goal: weighting the downhill ski. Use only those movements necessary to help you accomplish your objective.
Next: pressure on downhill ski.