For me, a core component of good singing is knowing how to breathe from deep within your body — from your diaphragm, the mass of muscle and tendons located between your lungs and abdomen. When I breathe in, I let the air fall low into my abdomen, expanding it (how you breathe when you sleep). The shoulders don't go up and the chest should not have much movement. Then I maintain sustained, controlled exhalation. I've found that good posture is also important when singing. It allows you to get a deep, full breath. If you slouch or scrunch up, your diaphragm locks and prevents you from getting a correct breath for singing.
A good vocalist will be able to maneuver through the vocal registers.
Chest Voice
The lower notes in your vocal register. Usually your speaking voice range. These notes vibrate in your chest as you sing them.
Head Voice
The higher notes in your vocal register. These notes vibrate in the back of your head as you sing them.
Mask or Mix Voice
The combination of your head and chest notes. You can feel these notes in the front of the face (sinus cavity areas). This is the area where you will see most vocal breaks as you transition from the low register to high register. Practicing scales, breathing techniques, and vocal workouts will help avoid breaks in your voice when transitioning from one range to the other.
I am sure there are many other techniques out there that work...these are the some that work for me....and staying relaxed, relaxed throat, lots and lots of water, and lots of practice.