I've been trying to learn to sing for 4 years now and after practicing and researching techniques and speaking to (incredibly hot) vocalists at the Institute, who can bloody wail!, everyone emphasises warm-ups to the Nth degree.

Warm-ups, then breathing techniques (intake, output, control), then posture/position. There are a million other things people say, but from my own experience, these are three big'uns. . .

This is a great thread, by the way. Loads of awesome advice!