theres a guy on this public acess show over here that sings fundamentalist-christian hyms whilst playing the guitar, and ive got to say that he hasnt gotten any better at singing by listening to himself....har har. maybe hes deaf, i dunno.

do simple breathing excersices and other stuff like that. learn how to sing your solos to a certain extent. im in a ska band and when i write songs, its usually just me and a guitar, so i hum the horn melodies out loud. it helps me get my songs better and my voice better, but ya gotta know when you suck and when you dont. be critical of your voice and get lessons when possible.