What kind of a sound is this person singing? What does the sound tell me about what is going on in the throat of the singer during that sound? What is going on in the body?
That is all you can work with. The vocal production has to be adjusted after it is over, so the next attempt can be done in a different manner. The only way to correct a vocal problem is to get a different attack. After you come in, you should leave your throat alone.
AFTER YOU COME IN YOU SHOULD LEAVE YOUR THROAT ALONE.
If you come in properly, your throat will go to a good place and you will be able to guide it to the exact sound you want as you sing, moment by moment by moment. If you do not come in properly, you have the first note to “adjust” through small changes of volume (breath pressure from the abs), mouth position or the placement of the front of the tongue, but after the first few moments, you have to leave the throat A L O N E.
After you have figured out what is happening, you have to decide if it is what should be happening. To do that, you have to understand balanced vocal function and balanced sound. If you don’t know what that is, understanding what’s happening in the vocalist’s throat and body won’t be of any use. If you understand that the sound emerging from the singer is less than optimal you have to decide in what way it is less than optimal. Then you must decide how to make the sound better by correcting the responses being made in the throat and/or body through exercise(s). That means you have to know what vocal or breathing exercises do when they are done well. You have to know what will compensate for wrong responses, what will develop weak responses and what will enhance responses that are good but not strong enough. You have to know how to deal with various kinds of confusion, lack of coordination and general lack of knowledge about what “good” singing is generically. You then have to address style.
If you want to help someone sing jazz you have to do exercises which allow the singer to go in that direction. That has nothing to do with developing classical “resonance in the mask”. If you correct the voice to balance in a way that does not suit the desires of the singer, it won’t be of any use. The singer won’t use the sounds and the balance will deteriorate and disappear. The exercises not only have to work with the throat and body, they have to work with the heart and the mind.
Then, you have to have educated ears about style. If you don’t know what authenticity is in a style, don’t teach it. Say you do not teach it. Stay away from it. If you only know one style, ask the student if that is a style they like and want to sing and teach that, but only that. If you wouldn’t know what a music theater sound does in a working actor that supports professional expectations, either find out or don’t teach music theater.
How different our profession would be if people were all on the same page with these simple points of view.