I've been looking for solutions to this problem, too. Particularly before bedtime. I'm having insomnia again and can't turn off my brain. My therapist suggested that I adopt a winding-down routine, a bedtime ritual. I don't currently have one.
For reducing stress generally, I guess any kind of exercise is good. It hasn't been helping me nearly enough, though. Perhaps I should do more.
Writing in my journal tends to help me to attain good insights, but it frequently gets me tense or agitated instead of calming me down. It seems to help other folks.
I like peppermint tea and find it soothing.
This weekend, I plan to try listening to classical music/opera while doing nothing else. In recent years, I have usually engaged in some other activity while I listen to music. In fact, I usually listen to music only in my car. So maybe rediscovering music as an activity in and of itself will help me just as it seems to help others.
I would like to cuddle up with my partner more before we go to sleep at night, but he has a bad habit of staying up late. This drives me nuts. I always have more trouble sleeping when he isn't there with me. Perhaps I should be more adamant about this, but he hates to be disturbed when he's role-playing.

Communing with animals is good. I have two cats that love to be brushed. I should do it more often. It makes me feel peaceful.
Sorry such a mischmasch. I'm avoiding doing something unpleasant, and the cracks in my armor are starting to show.