Well ~~ opinions do vary, natch. To my mind, diction, articulation, whichever term one favours, is the vital ingredient. Not the only one: imponderables like integrity of approach, oneness with the genre, also come into it; which is why I personally don't take to Britten/Pears folk arrangements ~~ for all his excellence as a composer, I don't think Britten ever really worked out what made the folk genre tick, or he wouldn't have used those grossly over-elaborate piano flourishes. And even then, as in the Lykewake Dirge in Serenade for Tenor, Horn & Strings, I think they bring it off for once.

But, I repeat, start with your articulation & work outwards from there, whether in narrative or any other sort of song.

~M~