To the extent you can, make sure your room is as dark as possible and as quiet as possible. Try dropping the temperature a little - either turn the heating down or the air conditioning up, depending on the season and what you have available. Avoid eating too late, and avoid caffeine in the evening. Avoid doing things other than sleeping in your bedroom - if you're always watching TV, reading, exercising etc in there you can easily form a mental notion that this is a room for anything except sleeping. Try and avoid using screens for an hour or so before bed and avoid anythign with bright blue lights (if you have a device with a screen that offers "night mode" try using it - it reduces the blue light and gives everything a visible yellow tinge).
Beyond that, I sometimes find taking a melatonin tablet before bed helps me sleep but given what you've said about your assorted issues you should talk to your doctor before taking any new medications.
