Tree Pose is an excellent practice to root and balance your first chakra, as well as to stabilize your legs and feet (any discomfort in these areas of your body is a definite sign of first chakra imbalance). Studies have shown that the practice of Tree Pose has positive effects on overall balance, stability, and physical coordination.
Begin in Mountain Pose (see prior description for details). Close your eyes here and imagine your favorite tree. It could be a tree you used to climb during childhood. I personally love to imagine the bodhi tree, under which the Buddha gained enlightenment. Though I have not yet seen it in real life, its large roots and widespread branches suggest comfort and security.
Trees inspire because they are stable, rooted firmly in the earth. As you plant one foot firmly in the ground, feel yourself rooting more deeply into the earth. Imagine that you are as grounded as Goddess Shailputri, that nothing can shake your resolve. From this place of inner resolution, slowly lift your opposite leg and place your foot on your standing leg, either below or above your knee, but never right on your knee.
Keep your hands pressed together, with your thumbs touching your heart, then extend them above your head. As you stand on one leg, contemplate how you can be like Goddess Shailputri and live with greater resolve to know your true Self.