Possibly my favourite singer ever is Billy Holiday. She had very little range and really, no tone or "sound" that would get anybody's attention, but she could take that beat up, raggedy instrument and sing like an angel.

I found Steve T's, comment about emotion interesting. This would be a case where a good teacher, or an honest critic could be helpful. Someone who is over-emoting can be downright embarrassing to listen to, but of course feeling is the magic ingredient. I know I'm not a very good singer myself, so I just focus on getting the tune right. If the song is good, people like it fine so long as you don't hurt their ears.

Frank I.T.S.