Go to sleep at the same time every night - don't take naps in between.
Avoid caffeine, nicotine, alcohol or stimulants.
Triptophan (sp?) use to help, i.e. pills, cottage cheese or milk, but think it's been banned.
Exercise during the day.
Don't fight it! If I can't aleep I get up & read, watch tv etc until I am tired. Some schools of thought are to stay in bed. If you can, great - if not get up & do whatever until you are sleepy. Sometimes I play computer games - clears my head of stress.
Have a cozy/compy sleeping environment - sheets/pillow/blankies/mattress. Drown out outside or inside disturbances. Get blackout shades/curtains. I sometimes only get about 4-5 hours. But, that's better to me than sleeping over 8 hours.
If the problem continues, seek out a doc's advice.