I'm not a lawyer, but I have watched a lot of Law and Order, so I feel some amount of confidence in my courtroom expertise. In a similar way, I'm not a vocal teacher, but I have spent the last 25 years playing for hundreds of voice teachers and choir directors. Some of them are famous in their field. Most are not. Since I have a compendium of knowledge that would be tragic if lost, I have distilled my years of experience into 10 easy steps which any singer can follow. Since many vocal teachers can be confusing (phonascus obscurum syndrome), I have added some clarifying comments.
1. Breathe in the shape of the vowel. Since there are about 19 different vowel sounds in English alone, you have lot of breathing to learn. Once you master the English vowels, you can progress to der Umlaut breathing exercises.
2. When you sing, drop your jaw North and South, not East and West. North North East by South South West is also acceptable. When you press into the NorthEast and SouthWest jaw dropping, you are approaching the danger area, and East North East and West South West are right out. Obviously, if you live in the Southern Hemisphere, everything needs to be inverted, so drop your jaw South and North.
3. When you sing, think of the vowel as a circle of sound. After you can imagine the circle, imagine the vowel as a trapezoid of sound and then a rhombus. Finally, imagine the vowel as a triangle with angles of 92, 68, and 20 degrees.
4. For an open throat, imagine the beginning of a yawn with a softball sized scoop of canard à l'Orange with pomme de terre and arugula salad in the back of your mouth.
5. Keep the tone forward in the mask of the face..but not too far forward and not too high or low in the mask. Once the tone starts slipping into the side of the mask, you are in deep trouble. If you find yourself in this situation, it's best to begin by placing the tone in the left eye. From there, progress to the left ear and gradually work your way around the back of the head and then move back around to the center.
6. When you sing with your whole body, the sound will seem to come from the depths of your soul. At first, it may be difficult to sense where your soul is located, but as your singing develops, you will begin to feel a sensation roughly between the kidneys and the adrenal glands. That's where your soul is. As you mature, you will be able to use not only the depths of your soul but you will also have access to the shallow end and wading pool.
7. When you sing, think of your body as a tree. Your head is a branch with new leaves and a birds nest. Your body is the trunk with initials carved in the trunk inside a heart shape. Your feet are the roots which a small dog is using...actually, I don't think I've ever understood this one.
8. Breathe from your diaphragm. Since it isn't really possible to breathe without your diaphragm, I also encourage the use of lungs. Some teachers prefer to use clearer imagery for the instruction of breathing like "breathe from the abdominal muscles", or "breathe from your pelvic muscles." I was surprised to learn that most people in the medical profession are simply unaware of the role of the pelvic muscles in the breathing mechanism.
9. Once you have mastered singing with proper pressure from your abdomen, imagining a large enough object in your mouth, centering the tone placement, and dropping your jaw, add vibrato. Now take it away. Now try things in different combinations. Vibrato, a small live bird in your mouth, jaw East by Northeast, breathing with diaphragm and pelvic muscles but not abdomen. The possibilities are endlessly fun.
10. Sing in tune.