A couple things you could try!:
1. Do some strenuous physical activity! If you are having trouble relaxing your left hand and wrist, then maybe incorporate exercises that use your hands and wrists.
2. Give your hand and wrist a short massage before WILD.
3. Try tensing the muscles in your hand and wrist really tightly, hold it for a few seconds, then relax them. Then repeat if needed.
4. Focus on the sensation of gravity and weight in your hand and wrist. Feel your limb sinking downward while you imagine the tissues softening.
5. Stretch the muscles in your hand and wrist before WILD.