I've suffered from insomnia for years - since a family bereavement. I have found it very difficult to control and the only thing that's had an impact is to deal with how I feel about the bereavement. But that's hard and it took me 5 years to be ready to do that. So the only sure fire way of dealing with it is to deal with the underlying issue.
But for quick fixes, herbal pills have helped me in the past, but not always. Rest and calm before bedtime is good - a bath, quiet time, no exciting TV for an hour or so before bed, stuff like that. Yoga has been a key coping mechanism for me - and meditation classes with my yoga teacher. He's taught me breathing and meditation techniques that I can use to slow myself down and get my body some rest even if I'm not asleep. I always find that the physical exhaustion is one of the worst parts of insomnia. Yoga gives me some control of myself.
If there's lots on your mind can you share it with a friend or your partner? Things often seem insurmountable in the middle of the night but if you chat through them you can find solutions or just ease the burden on yourself.
And a routine. Starting an hour or so out from bedtime and preparing your body and mind for bed can help.
But really, it's only dealing with the things keeping you awake that will enable you to sleep.