Well, for people who are having trouble getting to sleep, I'm going to give the same advice I always give:
  • Don't drink coffee or caffeinated drinks. Caffeine screws with you.
  • Stay away from junk food and stuff with sugar in. Especially soft-drinks! Chocolate, etc, also. Sugar screws with you. This goes not just for before bed, but the whole day. Keep your junk food intake to an absolute minimum!
  • Get some exercise mid-afternoon. This will help immensely.
  • Regularise your sleep schedule. Go to bed and wake up at the same time, or close to, every night throughout the week.
  • Have a hot shower or bath before bed.

Diet, exercise, and sleep schedule have a MASSIVE effect on how easy it is to get to sleep, and the quality of sleep too.