I've had insomnia for a long time and was on sleeping tablets for years before I realised they were making the situation worse. I've tried everything. Being the right temperature is key in this. I'll list a few things that I genuinely do think help.
100% cotton bedding and nightwear
Wool duvet, pillows etc. They're expensive but made a massive difference to me
Make sure the bed is properly made. Wrinkly sheets are horrible.
A cold bedroom - I feel the cold but the radiator in our bedroom is off
I need it to be as dark and quiet as possible. So we have blackout blinds, no ticking clocks etc
Not going into the bedroom unless to sleep. I will put clothes in the wardrobe etc, but do not sit in there
When I get into bed, I do this breathing technique, which is breathe in with mouth closed for 4 seconds, hold my breath for 7 seconds and breathe out for 8 seconds with mouth open making a whooshing sound. Do this up to 4 times.
I try to shower before I go to bed, but if I'm too tired, I'll just have a wash and then moisturise my body, massaging it in. I then do the same with my face and some hand cream just before I turn the light off. I use soothing fragrances and can smell the fragrances when I lie down which is nice.
Clean bedding always makes me sleep better, so I change my bedding regularly. Likewise I change my nightwear very regularly.
I also try to keep our bedroom as nice and uncluttered as possible, with a furry rug by my side of the bed and minimal things on my bedside table, just what I'll need, hand cream, tissues etc. I do like having flowers. Likewise, I'm a tyrant with the no clutter rule on my partner's side of the bed and bedside table! Anything to make going to bed as nice as possible and not being woken up when he tries to reach for something and knocks off 5 books, an ipad, mobile, glasses, a glass of water, a box of tissues, a comb and god knows what else.