This posture requires strong legs, strong core, and flexilibility of shoulders and hips. It’s a challenging posture for beginners, so you can try a modified one as shown below.
Basics of any standing postures
1. connect the front foot and the back foot to press each other, as you tuck the legs into the hips firmly and keep the hips stable, so it is counterbalanced and the posture should be more stable and more deepened.
2. Try to shift the weight onto the back leg as much as possible.
3. the tail bone, the spine, the neck and the head should be aligned and lengthened.
4. Engage the psoas.
As follow the basic
1. Separate the feet a leg width apart, Align the front foot with the back heal. The front foot should be straight forward, the back toe should be inward to keep the back heal onto the mat firmly.
2. The hips should be squared, The front shin should be vertical against the floor. The back leg should be stretched out. The front thigh is adducted and externally rotated, The back thigh is adducted and externally rotated.
3. (On the side as shown above)Twist the body to right side, press the left upper arm firmly on to the right thigh. Align the spine with the back leg.
(Modified one)Put the palms together, align the forearms, and keep the forearms vertical against the floor. Both upper arms are abducted and externally rotated. Look behind or upwards.
(Original one) As you press the left upper arm on to the right thigh firmly, put the left hand on the mat just outside of the right foot. The left upper arm should be adducted and externally rotated, The right upper arm should be abducted and rotated externally. stretch the right arm, spread and stretch the fingers. Look at the right hand.