Well I don't want to sound cocky or anything, but I consider myself a pretty good singer. I'm in 3 different bands and plan on attending Berklee. One thing you really have to get down when singing is relative pitch. That's only one aspect of course. There's also intonation, breathing, inner acoustics, and etc. Another thing related to relative pitch is perfect pitch. I don't think perfect pitch is neccesary but it would definately make someone stand out as a musician (Jimi Hendrix had perfect pitch). Anyway look around online and master relative pitch.
Good Luck and never let the music stop