If you can, set up a routine and stick to it. So pick a time, make a warm uncaffeinated drink, cleanse/tone/moisturise, go to bed and maybe play white noise or rain sounds etc. Make sure your bedroom isn't too warm. And try not to read in bed: better to read elsewhere and then go to bed, so you train your body into expecting no mental stimulation in bed. Bed is for sleep or sex only.
If you wake up and can't get back to sleep, get up and go to the loo, maybe get a drink and read for half an hour, then go back to bed again. This used to help a lot, but with the caveat that if you're disabled/ill and in pain as I am now, you might be better off just resting and trying to meditate than going through the pain and hassle of getting out of bed. I've learned to accept that when I'm in too much pain to sleep, at least lying down affords me rest, and doing a body scan meditation can help me drift off again.
If you feel the need for chemical help, avoid sleeping tablets unless a)you can allow yourself a full 8 hours of uninterrupted sleep once it's taken effect and b)you consider them as temporary to help establish a routine, or just have the comfort you have a couple available should you need them, which can often in itself mean you won't need them. You can also make occasional use of a drowsy anti-histamine like Phenergan, which you can buy OTC at a 25mg dose and which can be as effective as sleeping tablets, without being addictive and with far less of a hangover in the morning. This was my GP's preferred option before handing out actual sleeping tablets.
Insomnia is horrible. Good luck, and sleep well tonight 