Maintain a neutral spine
Maintain a squat at around 45 deg of hip flexion (stay low)
Keep a quiet lower body
Keep your knees mostly over your feet
If you don’t have a partner you can toss the ball against a wall.
You can use a heavier or more elastic ball to enhance the challenge.
Against a wall, a medicine ball provides to concentric effort. An weighted elastic ball enhances eccentric effort.
The med ball version will be better for snowboarders and the elastic weighted ball will be better for skiers.