Stand up and move around. While getting in and out of your seat can be a hassle, especially on a smaller airplane, moving around every 2 hours or so is the best way to prevent blood clots.
Flex and extend your toes. If you can't get up and move around, point your toes and your feet all the way forward, then raise them back up. Do this at least 10 times every hour. This simple movement keeps the blood flowing.
Wear compression stockings or socks. These can be found in any pharmacy and most department stores. They work by compressing your leg from the bottom up, almost as a massage that encourages blood flow.
Stay awake. Taking small naps is fine, but if you sleep soundly for more than 3 hours, you are increasing your chances of developing a blood clot. Therefore, it is best to limit your alcohol consumption and to not take sleeping pills on a long flight, even a red-eye.
Avoid crossing your legs or ankles. Having your legs or ankles in a crossed position for a long period of time restricts the blood flow even more, increasing your risk of developing deep vein thrombosis.
