Herbal tea like Sleepytime or Nighty Night that you can get at most grocery stores. There is also a supplement called melatonin that can help. Turn off all electronics, and focus on your breathing and relaxing your body.
I have had a lot of trouble with this in the past so I know my stuff. First of all I would recommend to stay away from caffeine after 1 in the after noon. Also if you ever take naps in the day limit them to half an hour. When actually lying in bed, try lying on your back and taking long slow deep breaths. Inhale through your nose and exhale through your mouth. It may make you fell light headed but it will go away. Another thing you can try is melatonin. It is an all natural supplement that is taken before bed. It increases a hormone in your body that helps you fall asleep. I stay away from sleeping aids. Last of all if you are REALLY having a problem take a benadryl, BUT ONLY IF YOU REALLY CAN'T SLEEP. hope this helped. Sleep well :)