QUOTE(rosfrog @ Aug 14 2008, 01:28 PM)

I would add that not enough singing teachers are properly versed in vocal anatomy and therefore end up using daft imagery like 'imagine you have a hot potato in the back of your throat' which tells the student precisely nothing - a good knowledge of vocal anatomy, what's in there, what impact it has on sound, how to control it voluntarily, will change the way you think about singing and make you a better teacher for it. It's fascinating stuff, too!
... although sometimes it is good to be able to use both imagery and anatomy
Some students respond well to all sorts of imagery while they just look at you in complete disbelief if you talk about a tilted larynx or the function of the cricothyroid muscle.
Although I completely agree that the teacher should know about vocal anatomy - but if they necessarily talk about it to the student is a completely different matter, because it might actually cause confusion.
In many cases, the hot potato-image might even work better than saying "raise your soft palate", because the latter doesn't say HOW, while a strong image usually evokes a physical reaction. But it really very much depends on the student and the type of learner they are.
To the OP: You are never too old. What you really need is a sound knowledge of what you plan to do, a good vocal technique and an absolute love for teaching. It is not a second best solution for people who did not make it as singers themselves (sometimes you hear the nasty sentence "The ones who can't do it teach"), but a real vocation. It is mentally and physically exhausting, but so rewarding, and I wouldn't want to do anything else. But you have to come a long way.
Although I have paper qualifications myself, I still say that they are not the most important thing (although a teaching course will probably be very helpful). But I would start off under supervision of a good teacher ...