Set a Schedule
Have a bed time. Make sure that you get to bed at the same time, or as near to it, as you can every night.
Blot out the Lights
Having light coming into where you sleep can be bad for your sleep patterns because they disrupt the physical cues that say it’s time to sleep. If you think this may be true, then keep things as dark as possible.
Make sure your food is digested and that you’ve drawn all the energy you can from it before you try to sleep.
Don’t Drink Either
Same story with drinking. If you’re thirsty, go for a cup of water.
Make sure that you do this more often than not. An occasional lapse is permissible, as your body will adapt and put you back on schedule.