A couple tips from
Singwise...
"The head should be held neither too high nor too low but remain in the communicative position of normal speech. This consistent posture helps to create a more balanced voice training session and, eventually, a more pleasing performance."
and...
"Raising the chin or head does not free the larynx. Nor does using the head to reach for high notes enable the vocalist to sing those higher pitches. Instead, tension is created, and accessing the upper register becomes more difficult, if not unlikely."