Things I've tried and sometimes they work: Slow your breathing; this happens anyway when you fall asleep and sometimes you can trick your mind that you're shutting down for the night. Silently repeat the word "sleep" over and over. If you're worrying about something, this distracts your subconscious. It's boring, but that's part of the idea. Get you room really dark or wear a sleep mask. If you make a habit of wearing a sleep mask, lying down and putting it on becomes a signal to your subconscious that, again, you're shutting down for the night. And you'd be surprised at how a little light can keep you awake, especially is you're already "wakeful."
No caffeine for at least 1-2 hours before bed and take some Melatonin about 20 minutes before you lay down. Melatonin is completely non-addictive and it doesn't cause any harmful side effects either. If you have tried every home remedy known to man, then talk to your doctor and see what he/she recommends you should do.