This might be a little late for your the call back tip you asked.. But anyways, before singing , do warm ups. Literally, do excercise,bend your waist, your neck and excercise facial muscles.. Massage your jaw while acting like you are chewing a big gum..also do a lip trill, it's like doing a bubbling(swimming excercise) but of course only not in water.. Try lip trill from a low note to high note and vice versa. Next stick your tongue out as much as possible. This will lessen the tension during singing(you know that time where your tongue feels like it's curling up)..shout HEY! loudly as if you're calling out someone, from the diaphragm and not from the throat because that would hurt. And oh, try jogging in place while singing a piece, this would loosen up your voice because you'd have to force yourself to sing louder inorder to hit the right notes while jogging. These tips might sound funny but these are just some tips i learned during my lessons..and it helped me a lot.hope this will helo you too good luck lindsey