Beginner: Beginners benefit greatly from forward fold, as it stretches the leg muscles where we most commonly hold on to tightness. Feel the weight of the head as you fold forward. Be mindful of your body. Do you feel any pain behind the knees or near the tail bone? If so, bend your knees deeply until that tension is relieved. Only go to your limit. That is your perfect expression of the pose.
Advanced: Advanced practicioners can continue to benefit from this posture. To deepen your fold, lay your chest on the thighs as you deeply bend the knees. Now, as you straighten your legs, keep your chest glued to the thighs - the strength here comes from your abdominals and hip flexors. Engage mula bandha as you stretch your upper body towards the earth and your tail towards the sky - feel the expression of perfect opposition.