Hang from a vertical object with a wide grip and bring your body to a horizontal position.
The legs are straight and aligned with the upper body.
Pull with the top arm and engage the scapula ( Shoulder depression ); push with the bottom arm.
Abs should be tight; avoid arching the lower back.
If you have trouble lifting your hips high enough, try starting from the top position ( Inversion human flag ).
The angle between your arms should be somewhere around 90 to 100 degrees. Having a grip that is either too wide or too narrow will make the exercise harder.