Standard advice:
Routine so your body unwinds naturally
No coffee after 14:00
No devices after a set time 8 or 9.
Breathing exercises
Plan next day early, so it's done and not on your mind.
Exercise, including walks.
Personally, my body clock struggles to keep the routine for any length of time. I end up with a single short sleep cycle and then I struggle to fall back asleep.
So, I have the combo of thinking of steps in a pet project. Something light and stress free, while listening to low volume history podcasts with earbuds on, to avoid getting disturbed by partner snorings etc.
It has to be both, having something my mind can dwell on without thinking too hard and the low volume podcast, so my mind can shift between them.
In the time it's taken me to type that out, I can be asleep. Other low volume stuff is fine too. ASMR whispers or soft spoken audio stories work too. It's to set up a consistent tone, and someone speaking about a subject for an hour does the trick. You get the added bonus of remembering some historical facts out of nowhere too.