Your ski belt should sit low to distribute the force over your hips and bum. If the belt sits too high, you risk back pain and other injuries.
Start by fastening the clip in front and tighten it. The belt should sit comfortably over your hips.
Then, attach the leg straps and adjust them to sit close to your body, without being uncomfortable. The leg straps help keep the belt in position when you are moving.
At last, adjust the front piece. For skiing, this strap should sit close to your body to help you maintain balance.