One thing I haven’t seen mentioned yet is to try and build up a pavlovian association with bed/bedroom = sleep. Don’t do any mentally stimulating tasks while in your bed or even bedroom - no TV or youtube, no mindless phone scrolling, no gaming, etc. Bedroom should be for sleep and sex, and that’s it. If you cut everything else out for a while, your brain will much more strongly associate bed(room) with sleepytime.
Other things people have mentioned are valid too. Consistent sleep schedule, don’t eat/drink/exercise for 2-3hrs before bed, etc.