But thanks to modern technology, youtube can serve as a mentor. I'm particularly taken with how well the cantor in this video handles the Psalm. Note that he seems to be singing it already before you hear any sound. He deliberately prepares himself mentally; he hears the pitch in his head and he already begins to pronounce the words. The Psalm really "exists" in his heart and soul before the last stage comes of actually making the sound. Then between each phrase, the rest of becomes part of the music. This is all very deliberate even if it sounds so natural and inevitable.
For those who are not interested in the art of Psalm singing, the piece itself is just wonderful and legendary: Allegri's Miserere. We are singing this on Good Friday. Most any parish can do it provided you have a soprano voice with a solid and vibratoless high C (ok, a tall order):