My voice teacher actually warns against the "mask" technique. It works for some people, when their instincts are right in the first place. However, feeling the mask does not guarantee that you are engaging in correct vocal production. You can be singing badly and feel the mask!

You need someone really, really good in order to insure that you don't get screwed up bigtime! It happened to me at Indianan University, one of the best music schools in the United States! Ask the person you choose to interview for the job whether (s)he understands vocal production fully, what kind of credentials (s)he has, whether or not they know what aritenoids are (tiny muscles used to "zip" the vocal chords closed), etc. Do some reading ahead of time about the voice and how it works.

Where do you live, by the way?

ciarili