i'm no singer, but most of singing is about musical ear... so understanding (western) music theory would be a very good start
but in terms of actual voice warm-ups... scale arpeggios are always good, doing them around all keys and in all the registers that you can reach with the vocal chords that your parents gave you. also i hear a few singers doing sort of sirens with their voices, going as high as they can get and moving down to as low as they can get.
i guess they help... but i'm a saxophonist, not a singer. my best advice would be good old google!