Some nights it's fall asleep as soon as I put my head on my pillow, some nights it takes an eternity. For those nights where it takes me forever to sleep, it took me about half a year to come up with a solution, and that was with my music.
I had decided to make a playlists of things that made me feel calm (and with metal, that isn't easy >_>) rather than make me feel alive. I made a playlist out of some cassical music, some game soundtracks (mainly Metroid ones) and some atmospheric/ambient metal tracks (mostly Space oriented/themed), and my room has to be pitch black.
The idea behind it was to set up an atmosphere which let me imagination run wild, like you would in a dream, using the darkness of the room as a canvas, and somehow it works for me.
also, you should never sleep without resolving an argument if you had one, else it will be on your mind and you wont be able to rest easy, I find.