No caffiene after 4:00 p.m.
Don't eat after 8:00 p.m.
You can train your body to go to sleep by doing the exact same bedtime routine every night. For example, I always take out my contacts, brush my teeth, scoop the litter boxes, wash my face, and then go to bed...in that order starting at 10:00 every night. I find that if I take out my contacts and brush my teeth early, I will fall asleep on the couch because my body knows that these are signs that it is time to sleep!
Make sure you go to bed at the same time every night and wake up at the same time every morning. You want to train your mind and body to fall asleep, and this kind of routine really works!
If you have tried to sleep for 30 minutes with no luck...get out of bed. Go to another room and read a really boring book or magazine or watch a really boring show on TV. Don't do anything interesting. If you fall asleep on the couch...that's fine -- at least you're sleeping! I challenge anyone to read something really boring in the middle of the night without falling asleep!
Don't do anything except sleep (and nookie!) in your bed. You want the bed to signal sleep, not anything that requires staying awake (reading, watching TV, work, etc).
Try to avoid sleeping pills. You can become psychologically and physically dependant on them. Thus, if you use them regularly you will find that you cannot sleep without them. Also, sleeping pills do not allow you to go into REM sleep which your body requires in order to feel rested. In addition, once you stop using the sleeping pills, you will experience REM-rebound during which you will have terrible nightmares, which will make falling asleep a scary thing to do and will contribute to the insomnia.
Overall...if you try all of these things, I am sure you will have success!