I try to imagine myself in another story. I allow myself to get lost in it and explore it.
While in general I may have negative thoughts throughout the day, before bed, I believe I rarely do. But not because they are not there. They are. It's because I fill my mind with what makes me calmer, and that is the stories I imagine.
It could be anything from traveling to someplace and meeting people, to more complex stories.
People may say that this normally could prevent them from falling asleep, but I find that it actually helps me fall asleep as I can easily get lost in the story and in my imagination. It helps keep my mind occupied with what I choose, rather than letting negative thoughts fill it up uncontrollably.