When learning a ballad, I find it helps to have a sense of the basic ballad verse format:-
                . _ . _ . _ . _
                . _ . _ . _
                . _ . _ . _ . _
                . _ . _ . _                           ( _ representing the rhythmic stresses)

I then work with the melody so that it sits on these pulses, and then I work with the text so that the significant words in each line will fall on the pulses.

Obviously, it's not always an immediate match, so that involves some adjustment which might mean altering the text, or settling for the occasional anomaly, which breaks the pattern and helps hold an audience's interest.

For example, a version of 'The Queen's four Maries' has a verse:-
               Last NICHT four MARies made Queen MARy's BED
with too many syllables for the basic pattern, but if sung with a sense of the pulse - rather than to a strict rhythm or time signature - it will carry the listeners because it's telling the story.

It all goes back to what Jim Carroll said in a earlier post -- "Sing it as you would speak it."