I sleep like shit most of the time. Not sure why, but here is what helps me.
I start with the mild shit, like that bullshit "sleepytime" tea. It's helped me in the past, and I'm not sure if it's because it actually has an active ingredient that does anything, or if it's because I just feel like a pussy making sleepytime tea and that makes me want to go to sleep to forget about it. Either way, I find that it actually helps.
Second is Valarian root. Really helps. It's actually similar chemically to valium, so It's bound to put you to sleep.
And if those don't work.
Finally, I grab an Ambien. Done. 8-9 hours of the most restfull sleep you'll have in your life. You'll wake up with a bladder about the size of a football. No groggyness either. I try to watch how much of this shit I take, as all sleep aids are somewhat habit forming.
I've never found melatonin to do anything for me.