This always helps for me.
Make sure its really quiet, music helps some people but it can be really distracting when you're trying to sleep.
Make sure you're completely relaxed.
Breathe in through your nose for 5 seconds, and out your mouth for 7
After a while your heart rate and blood pressure will lower and it'll make it easier to sleep.
After a while you can go to in for 7 seconds, out for 10