For me it was to spend time during the day to just think. This could be going for a 20 minute walk, or just lying in bed for 10 minutes or so with no phone or whatever. Let yourself be bored.

This way when it came to bedtime my thoughts aren't racing because I've already allowed my brain time to process them.

I think for many people when they go to bed it is the first time in the day they're not distracting themselves, and have time to just think. So all the thoughts from the whole day, or days, come rushing in at once and you feel like your "mind is racing". If you do this earlier in the day you might find it a lot easier to get to sleep.

Meditation builds skills that can be useful here.

When you notice your attention going to something you don’t want it to, acknowledge the thoughts and actively redirect your attention to something you want to think about.