Utthita Parsvakonasana is a posture for opening hips, strengthening the legs and the core, stretching the side of the body, twisting and many more. You can learn how to align the body through the posture.
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 you follow the basics
1. The front foot should be straight forward, separate the feet almost a leg width apart. The back foot could be at 90 degrees against the front foot, or toes slightly inward, and align the back heel with the front foot.
2. Most common mistake could be to bring the front knee beyond the ankle or the toes. Try to keep the front knee just above the heel or the middle of the foot. So, Front shin should be vertical agaist the floor, and the front thigh should be pararell to the floor.
3. Stretch the back leg out. Both legs should be abducted and both thighs should be rotated externally. The hips should be facing sidway. Almost same alignment as in Worrier pose B.
4. Put the hand or fingers just outside of the front foot. If you cannot put the hand on the mat because of the stiff hips, Use a block. The hand or fingers could be just touching with the floor, as you put the weight on to the back leg as much as you can.
5. Align the center of the body and the arm over the head with the back leg, Stretch the side of the body, and twist the body to bring the chest up to the ceiling, look at the hand over the head.