kinjalkishor 
Try to empty your mind and think nothing for some minutes, cut any thought that comes.
Tratak yoga (non stop gazing at a point for some minutes) will also help.
Reading boring subject books also works.
You need to be tired also to sleep, too much tired is also bad.
Any kind of anxiety or worry will make sleeping difficult. Try to methodically remove anxiety and worry causing problems from your life with proper planning and all of that can be done in day after good sleep, so do not waste your sleep on them.
Keep lights completely off.
Maintain comfortable temperature and proper ventilation in bed room.
Drink Warm milk before sleeping.
Sleep in completely quite place.
Do not try to think about anything before sleeping. You will fall sleep in minutes.
Earlier you sleep earlier you can wake up.
Sleep only required hours and at a specific time daily.