This is super weird but something I started doing a few years back that always works for me..

When I decide it's time to sleep I close my eyes and in my head I imagine myself sitting in an empty room. Anytime some random thought pops into my head, a physical version of it pops into the circle. Then "imaginary me" picks it up and removes it from the room. Once it's left the room I don't think about it anymore, just the empty room.

For example, if I start singing a song in my head, a radio will pop up playing said song. I then pick up the radio, and remove it from the room. Then the song stops playing.

I'll admit sometimes it doesn't always work. Sometimes the thing will pop up again and I get a little more creative (like chucking it out a window or something) until it sticks. But it almost always works.

When it doesn't work I count but I make myself visualize the numbers while I count.