Balance is by far the most important aspect of Tai Chi. You are not only learning physical balance (like standing on one leg), but trying to balance yourself mentally, emotionally and spiritually. Basically trying to balance everything in your life, your health, your time and your energy. In a nut shell, Tai Chi is balance itself. The whole form is balanced and designed to balance you externally and internally. Once you have a good center of balance in your Tai Chi form, you will find that your training will bring you the great benefits that the style was created to do and slowly pour into all aspects of your life.
So, where do you begin? Unfortunately, many people find it difficult to get out of the habit of thinking of each individual posture. Things like; where your hands go, where to step and where to put your feet. People tend to think of each posture in the systematic way in which they learned them. Don't think of each posture as a separate movement but instead think of each posture as a part of the whole. Where the whole body moves as a unit, the feet moving in perfect harmony with the hands, while the knees move in perfect harmony with the elbows, the hips are in harmony with the shoulders and the top of the head moves in perfect harmony with the dantian (about 3 inches below the navel) and all the movements originate from the waist. The energy for all movements must begin at the waist (dantian) and travel down the legs to the bottom of the feet, to an acupuncture point called the bubbling well, bouncing back up the legs through the waist, up the spine and finally through the arms for the final strike.
This is why it has always been said (in the Tai Chi classics) that the waist is the ruler. Therefore, all movements must come from the waist, whether that be a hand movement or a step. You must get into the good habit of causing each movement to come from the waist, make the waist cause each movement. This will seem awkward at first, and you will only be able to manage large movements. But as you progress in this way of training, you will notice the movements becoming smaller and smaller as the body becomes completely in syn. It will appear as if there is no waist movement at all, because the waist will cause the movement from within.