There are some good suggestions in this thread already. Try starting with some basic sleep hygiene.
1) Reduce the amount of stimulation your brain receives before bed:
Your bed is for sleeping and sleeping only. Avoid playing with your smartphone or reading in bed.
You should stop using light-emitting electronics (PC, smartphones, etc) before going to bed.
Exercise regularly but preferably more than a couple of hours before bedtime contrary to popular belief exercising right before sleeping will only stimulate you more.
Avoid coffee, alcohol or nicotine.
If there are worries keeping you awake at night, look into addressing those.
2) Sleep at the right time:
Maintain a regular sleep schedule especially a regular wake-up time.
Try to avoid taking daytime naps.
You can always look into professional help. If you don't like the idea of medications there is clinical proof that cognitive behavioral therapy can be effective with sleeping disorders. The best way to go about this would be seeing a sleep specialist.
Best of luck.
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