Below is my general sleep guide.

From your post these points sound the most relevant:

• Once in bed, no work/study/planning thoughts. Identify and then free your mind of any thought patterns which keep your mind going. Resolve to address them at another time.
• You can even pre-allocate a time to resolve them during regular waking hours. eg. before getting into bed, remind yourself that any thoughts which 'need attention' will be resolved at '12pm tomorrow' or 'during your commute' etc. If they pop up during the night, you already have a precooked answer which doesn't involve waking your brain up even more.
• Don't keep looking at the clock or trying to calculate how many hours of sleep you can get.
• Avoid looking at phone screen once you're in bed, if you need to adjust volume use buttons or remote etc with your eyes still closed.

General

• Observe if caffeine plays a role, you can eg. avoid it after lunch or after dinner - whatever works for you & your body.

Late Evening

• Avoid cold (bluer) colour lighting & use warm (redder) colour lighting from late evening until bed. This is important and melatonin effectiveness is directly controlled by this ^1^. To put it very very simply, we've evolved for redder light = sunset->sleep, bluer = day->awake. Angle of the light can also play a role if you want to go deeper into it.
• Schedule blue light filters on your phone & computers. Should be standard on modern phones & use something like f.lux for computer ^2^.

Before Bed

• Avoid alcohol, lots of sugar or sugary drinks for at least an hour or so before bed.
• Some other otc/"natural" sleep aids to consider: l-tryptophan, valarian, hops, passion flower, chammomile. There's some 'complex' products which are basically derived from these kinds of things eg. ^3^. [Always check anything you take for possible interactions with eachother or medication you're on].
• Supplements like magnesium can help reduce effects of muscle tension.
• Ensure any herbal teas or other foods, drinks etc don't contain more caffeine than you'd planned for. eg. some chocolates contain caffeine.
• Showering or bathing just before bed can help you relax.

In Bed

• Once in bed, don't keep looking at the clock or keep trying to calculate how many hours of sleep you can get.
• No work/study/planning thoughts. Identify and then free your mind of any thought patterns which keep your mind going. Resolve to address them at another time.
• Is temperature or air flow effecting you? Some people find an oscillating fan can help regulate the airflow & temperature, and the repetition can be soothing.
• Are sounds keeping you alert or waking you up? Consider fan, white noise machine or rain sounds ^4^. You can adjust the EQ to mask specific problem sounds, eg. bass for thumps, mids/high for clatter or voices etc.
• Is light making problems? eg. light from electronics in standby mode, light coming through or around edges of windows, other lights in the house? Identify and cover them or your eyes as needed. Remember blue light is not your friend at this time, blue LEDs might look nice but can mess with the brain chemistry of sleep ^1^
• Avoid looking at phone screen once you're in bed, if you need to adjust volume use buttons with your eyes still closed.

Sound

Falling asleep to sounds can sometimes help. Different people like different things on different occasions: music, YT, movies, TV, audio books, ambient soundtracks (rainforest, crackling fire), even boring monotone talking can be good. Avoid any ads if streaming or TV as they're designed to grab your attention.

There are music genres almost designed for sleep, various ambient genres can be great especially if they employ low frequency variations and alpha, theta and delta wave type transitions ^5^. There's a bit of bs around this, but also some legit bio-entrainment science too. In general find what works for you.

If listening, consider using your phone & use a sleep timer app on your phone to automatically gradually lower the volume and switch off after a scheduled time, this can help avoid being woken up by it later in the night. Find the timer periods which work for you. Also ensure your alarm will still wake you.

References

^1^ https://academic.oup.com/jcem/article-abstract/88/9/4502/2845835

^2^ https://justgetflux.com/

^3^ https://www.flordis.com.au/products/redormin-forte/

^4^ https://www.youtube.com/watch?v=7JyE47-Ykjo [Download rather than stream to avoid interrupts/ads during the night.]

^5^ https://en.wikipedia.org/wiki/Electroencephalography#Wave_patterns