I don't think I've ever used a song title, but sometimes as I'm working on a story I'll realize that a song line or a poem line captures the theme of what I'm working on. My last fandom I used a lot of quotes from the show. Usually, I'll stumble over something that works as a title eventually, but sometimes I don't, and then I just title it whatever the fic is about, which means I've got a mix of fics called "And Bathed Every Veyne" with fics called "It Was Long, Your Message" with fics called "Eating Pie."

Parentheses are evil unless it's a remix.