Because I sang, I went to New York to do opera and then did Broadway to support myself, and then, when I divorced and had a baby to support, I went on the road singing for YEARS! To keep my band and myself working, I sang every kind of music there is. Including rock and roll and disco, which, I might add, I learned to love. 😉
The conclusion I came to is that singing is all about muscles. Now OBVIOUSLY you have to sing correctly, but it’s not enough to sing correctly-you have to work the muscles. And if you have strong muscles, you can sing over anything and everything except laryngitis and one other bug that makes you cough and your throat tickle constantly.
I give you a working knowledge of your voice and how to use it. Most of my students who have been with me for years have three to four octave ranges and can sing anything and everything they want with power and confidence.
I have “songfests” about every three months where my students get up to sing at a Karaoke restaurant (without the words in front of them). I believe it’s important to get up in front of people often to walk through your fears -and we ALL have fears at first. And obviously, as with anything, practice makes perfect.