Take a melatonin pill, then read "light" fiction for about half an hour. If that doesn't work I'll take something a little stronger than melatonin and watch Sportscenter until it kicks in!
I usually just do some reading and relax, trying to get my mind of various things I have to do the next day, this seems to make me fall asleep alot faster
My best advise for relaxing before going to sleep is to read a good book. By this I mean an interesting novel that grabs your attention. My rule of thumb is that if I fall asleep twice while reading...then I close the book and give in to the sandman.
I have difficulty to sleep. I drink a glass of wine before I go to bed, and that makes me easier to fall asleep.