Stand with the bases of your big toes touching, heels slightly apart (so that your second toes are parallel). Lift and spread your toes and the balls of your feet, then lay them softly down on the floor. Rock back and forth and side to side. Gradually reduce this swaying to a standstill, with your weight balanced evenly on the feet.
Firm your thigh muscles and lift the knee caps, without hardening your lower belly. Lift the inner ankles to strengthen the inner arches, then imagine a line of energy all the way up along your inner thighs to your groins, and from there through the core of your torso, neck, and head, and out through the crown of your head. Turn the upper thighs slightly inward. Lengthen your tailbone toward the floor and lift the pubis toward the navel.
Press your shoulder blades into your back, then widen them across and release them down your back. Without pushing your lower front ribs forward, lift the top of your sternum straight toward the ceiling. Widen your collarbones. Hang your arms beside the torso.
Balance the crown of your head directly over the center of your pelvis, with the underside of your chin parallel to the floor, throat soft, and the tongue wide and flat on the floor of your mouth. Soften your eyes.
Tadasana is usually the starting position for all the standing poses. But it's useful to practice Tadasana as a pose in itself. Stay in the pose for 30 seconds to 1 minute, breathing easily.