I used chapter titles in my first MS, but I shied away in subsequent manuscripts because I worry that they foreshadow too much and ruin some of the mystery. (agreeing with VoireyLinger)
Chrisla / Devil:
Susan Elizabeth Phillips is one of my favorite authors. I read a book recently where she had a quote at the beginning of each chapter (
THIS HEART OF MINE). Generally, the quotes were funny and added a little whimsy. They were snippets from her MC's Children's book or her MC's imagination. Her other books don't have the quotes, so it was unusual; but didn't detract from the story at all.
I hadn't thought of doing quotes; but pondering it now, I think it would take a little more planning and research than I'd enjoy to find (or make up) the perfect quote that fit the chapter without being a spoiler.
So to minimize work and risk of spoilers, I prefer to go with chapter numbers alone.