I found that writing thoughts down that were keeping me awake helped.
I also needed some medicinal help - in my case fluoxetine (Prozac) and Oxazepam - a mild tranquillizer.
Oddly, I also found that co-enzyme Q10+vitamin E helps me too if taken it in the evenings.
Also, avoid any caffeine or concentrated sources of sugar after 6pm, and if you take any stimulant medication, try to take it before the evening.
Don't eat too close to bedtime.
Hypnotherapy helped me too - my therapist gave me a CD and whenever I can't sleep, I play it through headphones and I normally get to sleep within half an hour of it finishing.
Also, I can't relax so I get a lot of muscle aches, stiffness, and sometimes spasms.
What helped with this (for me personally) was massaging the affected areas (espeically my calves) with Ruta Grav cream (homoepathic preparation). Also putting a pillow under my feet so my legs are slightly raised helped.
It also helps me to make sure the temperature and humidity in my room are comfortable for me as I am very sensitive to these and it keeps me awake. I use a fine mist spray bottle of water to humidify my room if the air is too 'dry' and I use heating and desk fans as necessary, depending on the weather, to regulate the temperature. Although you have to be careful of electricity bills - try and go for low energy consumption solutions.
Also make sure your bed and bed covers are comfortable and are not hurting your back or any other area of your body at all and also make sure the sheets and duvet and pillow are made of a fabric that you like the feel of and do not have any allergies or sensitivities to. Make sure the weight is comfortable for you.
I like the heaviness of a duvet, so even in summer I have to use a duvet - even if just a corner of it is resting on me, as a 'psychological prop' that makes things okay - I can't get to sleep with just a sheet as I need that feeling of weight.
These are just my individual experiences. I hope they may be of help to you in some way.