Step 1: The Basics
Step 2: Singing
A warmer and more humid area to play loosens up your vocal cords and may allow you a greater range when singing.
You're 12 and a half, Jimmy. Put off singing until your voice doesn't crack.
Have a Drink
Taking a swig of water every so often helps, but a fruit-flavored juice is much better. If you don't have a juice drink at your house, you can take a bite of a juicy fruit.
Look, singing on Expert is no fun at all. You have to sing like a robot. I suggest staying low on your levels. Unless you're a competitive player and you don't want to have fun.