I suffered from severe insomnia a few years back and I can tell you that it was horrible. As the insomnia got worse and worse so did my anxiety. Every night I would lay in bed worrying that I wouldn't go to sleep, which made it worse of course! Soon I wasn't sleeping at all and it got to the point that I had to see my doctor.
First off I want to say I am not a doctor. Do your own research and consult your doctor. This is just things that I have found to work for me, if you suffer from anxiety as well as insomnia, or the insomnia is severe or has lasted for more than a week you should go and see your doctor. Extended periods of insomnia not only become a vicious cycle but can be dangerous to your health and to your mental state. DO NOT listen to well meaning friends or family saying you will eventually sleep, this not only is bad advice but also can be dangerous.
Take Magnesium - Magnesium not only controls our central nervous system, but helps us deal with anxiety, stress, and helps with sleep. Caution! Take at first an hour before bed, if you are deficient as most Americans are it will make you really sleepy. The best magnesium is Magnesium Citrate, or Topical Magnesium as they are more readily absorb able to the body.
Listen to Something - When lying in bed a big problem for those that have insomnia is the obsessive thinking "Am I going to be able to sleep, I'm not going to sleep tonight" I have found that listening to books on CD set at a low volume is immensely helpful. I listen to Focus on The Families radio theater such as Anne of Green Gables and Little Women and fall asleep very quickly. My husband even finds them fine to listen to. These are not just books on tape but actual theater and Focus on the Family has dozens of books they have adapted. Listening to a calm and non exciting book on CD gets your mind off of fearful thinking.
Watch Something Non Exciting - Another option is if you have a TV in your room. Put on something like a nature show on DVD. Not a television channel because the commercials will come on and interrupt your sleep. You can usually put your TV on timer so it will go off automatically. I love nature shows because they are not too exciting and generally have soothing music. The one I use is Planet Earth and I like it because it has a dozen different episodes so I don't get board. I actually don't "watch" it really but after awhile just close my eyes and listen and drift off to sleep.
Listen to Guided Meditation - On Youtube there are dozens of guided meditations and also alpha and beta wave soothing music selections. The alpha and beta waves help soothe our brains and I do use them and find them helpful.