What I do, and works for me..:

1 - Quit Caffeine
2 - Use an eye mask (the darker the better)
3 - Use earplugs (eliminate any voice other than the beat of your own heart, which feels great!)
4 - A low dose Melatonin 2-3 times a week. (this may give heart palpitations as a side effect, luckily I don't have it, so always ask your doctor)
5 - LIGHT is your greatest enemy when it comes to sleep. Turn off your monitor / leave that smartPhone aside at least 30 minutes before sleeping.

I hope you find these beneficial :)