Some punk singer dude told me to pull your set of songs thru when you rehearse - either with your band or alone - just in one go, like you would do at a show live. Take time, go wild, jump around, mess up, go crazy, yell! Put in more calm tones, high, low, grunts, everything you can think off. Breath the max outta your lungs.
If you are so inclined you can record that stuff on a tape or something, to hear how you sound.
It's about seeing how your voice reacts in all the circumstances you put yourseld thru. You'll see what's possible and where you can go and where you wanna push yerself for where you wanna go.
I hope this is somewhat helpfull!
IDON



