Keep your bedroom as dark and quiet as possible. Wear a sleep mask if you need one, or just put a piece of cloth over your eyes. If there is too much sound from the next room or outside, try running a small fan (it needn't blow on you unless you want it to) so that the hum of the fan (called white sound) will "blur over" other sounds.
Make sure it is quiet in the house but if you sleep easier with noise try playing some peaceful music. Do not eat before bed but a glass of water may help. Also, take some Benadryl it will knock you out.
About 1 hour before bedtime, turn off the TV, phones, computer, music, etc. Maybe read or something. All these things usually keeps your mind so occupied that you can't get things out of your head. Let your mind relax, and be clear when it's time to go to sleep. Good luck. If you are a teen, you need 8 hrs a night!
If you have nightmares, I put perfume on my pillow and that helps. I have trouble sleeping a lot, so I usually put on some quiet, soothing music (that I actually like), and as many others have said, having your room completely dark helps a lot. I have glow-in-the-dark stars all over my walls and ceiling and sometimes I stare at those and make shapes out of them 'till I fall asleep.
There are alot of things you can do to ensure a long good night sleep. Some things are meditation and prayer before bed. If only for a while it relieves you of your worries so you can go to bed stress free. Another thing is, depending on the heat and humidity, you might want to open a window, especially if you're claustrophobic. Also, you can get a CD that has ocean and wind sounds on it. That is very calming, my mom use to play it when I was little to put me to sleep. You don't want to listen to any Lil Wayne or Drake or anything like that just calming music. Start making yourself go to bed early. On school or work days, I go to bed around 8:00 or 9:00. If I go to bed later, I don't get up on time, then myself and my sisters are late. Drinking chamomile tea is a good way to fall asleep if you aren't tired. No Caffeine after a certain point in the day. These little adjustments should help you have a better and restful sleep. Good Night!