Be very careful in this pose. Develop yourself on your feet before standing on your head. Align your body in Mountain Pose before attempting headstand. If neck not aligned properly it could cause undo strain on the neck vertebrae. Heads are not meant to bear weight. Instead, your head is merely one of the minor supporting points in the supportive triangles you create with your arms. Your shoulders and arms must be strong to keep the neck long - shoulders away from your ears. Stomach muscles firm. When first attempting use a wall as support. Inhale as you come up into headstand.
Breathe slow and steady.