Everything I've read and practiced focuses mostly on breathing and projection. Practice breathing from your core instead of your upper chest, it gives you more air to work with. Work on expanding your diaphragm everytime you're breathing in and out. Posture will play a part in how successful this is. I learned how to do these in band class in primary school - there are probably some good videos out there related to playing instruments that could teach you.
Basically think of your lungs as the instrument that you're pushing air through to make sounds.
I know that's probably not helpful
I took a look online as well and one of the most common comparisons is trying to teach someone to whistle. You explain a bit, they look at you funny, and then they try to make some sounds...and then BAM! They whistle, and suddenly everything you were saying now makes sense.
