Review meds, exercis. It depends on what is causing them. Lots of reasons exist for leg cramps, including medications, electrolyte problems, vascular problems, etc. If it is from a cholesterol drug called statins, then sometimes stopping or changing the medicine can help. Other times, over the counter medicines help, like naproxyn or ibuprofen. Coq-10 is a supplement that can help. Exercise may help too!
Evaluate cause. Leg cramps come on with tired, irritated muscle as a result of venous disease (which causes swelling), heavy exercise, prolonged working/standing. Low levels of potassium, calcium, magnesium, dehydration also contributes. Try stretching exercises, ice massages, repletion of minerals. See a phlebologist to have your leg veins evaluated.
Water, stretch, vits. Many people get leg cramps from not being well hydrated or not stretching their muscles enough. I would make sure that you are drinking adequate water during the day and not too much caffeine (makes you dehydrated). Gentle passive range of motion stretches can help. If this does not get rid of the cramps i would try adding a daily multivitamin/multimineral. If all that fails i would see a doctor.
Think about veins. It could be from over use. There is also a possibility that it could be related to too little iron, magnesium, potassium, or calcium in your blood. One of the most common symptoms of varicose veins and venous incompetence is leg cramps. As much as 65% of the time, people with varicose veins will have leg cramps. If you have any visible veins in your legs, see a vein specialist.