I always try to remove my shoes and elevate my legs a little at quite times during flights. By wearing shoes with leather inner lining, my feet don't even smell. It helps with potential swelling and lets you skin breath a little. I also massage them a little occasionally, to restore circulation. Wearing medium or firm support thights also helps better circulation, but they are a little pricey, you can get a pair in m&s for a fiver or two pairs at sainsburys for £4.50. These, as well as comfortable shoes work well for me.