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https://www.musicbanter.com/games-li...litz-game.html )
Lots of famous song writers get asked this question, though I don't usually remember their answers. My instinct is that it's easier to fit words to a tune than it is to fit a tune to words, so I'd say start with the music.
Two pertinent comments supporting this approach that I more-or-less recall:-
Brian Eno: The problem with putting words to a piece of music is that people imagine that's what the song is about.
Jon Anderson: I chose words according to their sound as much as their meaning.