Begin in basic stance: 
Your feet are positioned directly under your hip bones, parallel to each other, and your weight is centered and distributed evenly over both soles. Your knees are slightly bent (soft), and your pelvis is tucked slightly under (pubic bone toward the navel) in the neutral position. Your ribcage is pulled up out of  your waist; your shoulder blades are pulled together and slightly down the spine. Your neck is long, in extension of your spine.

Pelvic drop:
Gently contract your abdominal and gluteus muscles to increase the slight tuck of the neutral position to a stronger pelvic tuck, then release the tuck and allow your pelvis to drop only as far as the neutral position. Your upper body should remain as still and separated as possible.