our sifu actually focused on these subjects today. I might need some help from other experts. Apparently, there are two types of flexibility. Static and dynamic. The latter should be practiced during intervals, in periods of 24 hrs to let the muscles and ligaments relax to gain strenght. One very good way to improve your flexibility is with a partner. Stand firmly next to a wall. Have your partner hold your leg up sideways and keep it so that both your legs form a 90 degree figure. After that tighten up your muscles while breathing in heavily, you'll feel your leg becomes heavier. After maybe 15 seconds, relax your leg and let it go. Let your partner pull your leg until you can't go any further and hold it for about 30 seconds or so. actually, there are plenty of other and im pretty sure someone is about to correct me on those two types of flexibilities. good luck