Take a little ZMA or GABA. If you really need, take some melatonin. I think people actually abuse melatonin too much, but if you take it for a couple of weeks it'll help to get your circadian rhythm in check. Clear your head before you sleep. If you have errands that you missed during the day, write them down and deal with it the next day. When you hit the sac, you should be doing it to sleep. If you aren't prepared to sleep, get up, watch some tv, go for a walk and try going to bed again.
If you don't fall asleep within the first 15 minutes, you shouldn't keep laying in bed. You'll just drive yourself insane and make your sleeping problem worse. I used to not sleep for days, now I sleep like a damn baby.