A large number of Taekwondo Stances require the practitioner to have one or both of his/her feet pointing straight forward. A large number of practitioner use their big toe as an indicator of whether or not the foot is straight. Herein lies the problem. If the big toe is pointing straight forward, the foot is not. Instead, point the second toe straight forward. If it is straight, so to is the foot.
This tip can drastically increase the stability of your stances. A large number of martial artists spend all their time focusing on the position of their feet, the weight distribution between their feet, and the exact location of their feet relative to each other and their body. You might be asking, “what else is there?” Your tailbone. In every stance your tailbone has a very specific location it should be pointing at and if it is, your stance’s structure (and balance) will be significantly improved. Typically, in a stance that has a weight distribution of 50/50 between the feet, the tailbone should be pointing to a spot at the middle of a line connecting the two feet. It wouldn’t be practical to go over the tailbone position for every stance, but this should give you enough to experiment with.