All the years Ive played guitar could never get my vocals strong. I sing perfectly in tune and can harmonise like everyone who was raised on the Beatles should! Couple of singing lessons etc later still no go. Then I started thinking - if I can produce a vibrato - doesn't that mean that I am now singing 'properly'. So I started trying to find out how this is done. It seems like a best kept secret! Found this on the internet - but surely this can't be right ...
1. Place your hands at the bottom of your chest and feel where your ribs come together in the middle. Now move your hands slightly below this point. (it's the soft area a few centermeters above your belly button)
2. Now sing a note on one pitch in your easy range. Any note will do.
3. As you're singing this note, push in gently with your hands. The key is to push in, then pull out, and push in, then pull out and so on. Try doing this at a rate of around 3 to 4 cycles a second.
Listen to how your voice wavers in a singing vibrato like fashion.
Now it probably sounds a little exaggerated at this point, but this exercise is just to get things going.