Train yourself. Pavlov’s sleep. Every time you go to bed, watch/listen to the same thing. Eventually, your brain associate the thing with “time to sleep”. That’s how it works for me, anyway. I turn on the same movie and pass out in minutes. Don’t do it with one of your favorites, though.
And also, don’t do things like lay in bed watching TV or messing with your phone all the time. You want the bed to be mostly mentally associated with sleep