I swear by no caffeine, no sugar, exercise, light dinner, nothing to eat after 7pm, and a diet of non-toxic foods during the day.
Turn off TV and smartphones way before bedtime, especially the news and murder mysteries, etc. Remove your TV from the bedroom.
Create a sleep sanctuary. De-clutter the bedroom, make sure no light seeps into the room...not even a night-lite. Set the thermostat between 55 and 75 degrees. Make sure the AC/Heater is well filtered so allergens aren't in the air. Clean sheets...especially the pillowcases, preferably double pillowcased.
When you lie in bed, consciously relax as you tense and then relax each part of your body
Limit nap time to 15-30 minutes.
If you have any pain, get rid of it. Ibuprofen, aspirin, soak in warm bath of Epson Salts, or whatever it takes.