I have had four lessons with Juan Carlos Zepeda, with sessions divided into voice lessons and music skills (intervals, timing, etc.).
Juan Carlos has a way of demystifying how the voice works (head and chest voice, placement, etc.). Each session clears something away and my understanding of the mechanics of it all is increasing.
Juan Carlos has a beautiful singing voice, plays piano, and is both very kind and approachable.
I highly recommend him.