Buckeye.nurse gave some outstandingly excellent advice and I pretty much follow that regimen, in addition to this:
I keep a cup of valerian tea at my bedside. I have one glass of wine with my last meal before bedtime.
The coolest thing I ever discovered was regular breathing, repeating a mantra, and focusing on phosphenes.
Here's what I do when my mind won't shut off: First, I get into a regular breathing pattern to a count to 8 to 12. I focus on my breathing, inhaling entirely, exhaling entirely. Once my breathing is regular without counting, I say my mantra, something I repeat in my head over and over again. My favorite mantra is the Lord's Prayer. Deep, regular breathing and a mantra. Now comes the phosphenes.
Phosphenes are little blobs of light you seen when you close your eyes, caused by the intermittent firing of the optic nerve. Our brains won't allow us to see total blackness, so our optic nerve fires and we see those blobs of light.
I focus on those phosphenes and make pictures out of them, sort of like seeing images in clouds. I watch them move and swirl and show me things. I remember one of the first things I ever identified when I got into this technique: I saw a courgar jump off of a gas pump!
Regular breathing, mantra, and focusing on phosphenes has never failed to allow me to fall asleep as long as I do as I described. I've been through some major life crisis, and this technique, along with exercise, art, and some other things, has allowed me to fall asleep with almost 100% success.
I have also used, in the past, the Delta sleep System which includes a CD with some soothing flow of noises.
Good luck to you, melissaxoanne !