maintain a routine. Actually get up when your first alarm sounds. Do real physical activity during the day (every day, but less on off days is ok). Don't consume stimulants within 8 hours of bedtime. Don't consume too much depressants (this includes alcohol). DO NOT TAKE A SCREEN TO BED WITH YOU.

Hit most of these and you should be ok. If you're doing all of them and it still isn't working, maybe see a doctor.