Like Shalini, I have a vocal range of about an octave and a half, maybe a tone more. I find that with that range there are indeed very few traditional songs or recently composed songs in the folk idiom that I cannot sing if I wish to. Most songs in the repertoire are within that range.

The main things I have found useful are to know the highest and lowest notes that I can sing comfortably and to then pitch the song so that I stay within that range. Unlike art music, it is not necessary to sing a song in a particular key just because X sings it in that key or because it is in a book written in a particular key. Change the key to suit your voice. I agree wholeheartedly with the advice about relaxing and breathing properly - using the diaphragm. I also agree that telling the story is important and hence I always try to make sure that the words are clear and that I phrase the song properly.

I think the suggestion to sing in your natural voice encapsulates all these things because if you do that, you tend to do much of the above naturally.