From nothing is where you start, this is Wu Ji. Once you begin to move the nothing becomes something and you have Tai Chi.
The Wu Ji Posture is done in many different ways, but the basic concept is the same. So below I will describe how to do the posture.
Feet should be shoulder width apart, flat on the ground, and the weight distributed over the entire foot, yet it should feel as if most of the weight is centered just below your ankle and slightly forward of the heel.
Your knees should be slightly bent or soft and springy. The knees should never lock.
Your hips relaxed and level to the ground. Your tailbone should be slightly tucked in. In order to tuck the tailbone, image that you slightly lift the navel, which in turn straightens out the lower back and brining the tailbone slightly under.
Your back should be straight, not leaning side to side or tilting forward or rearward.
The shoulders are dropped and slightly rounded. The shoulder blades should not feel like they are squeezing together, yet they are not stretching apart to make you feel hunched over. When done correctly, your hands will lightly touch the thighs halfway between the front of the thigh and side of the thigh.
Your head should feel lifted up as if a string were pulling the crown of the head to the sky. Don’t let the head feel as if it were a bowling ball (dead weight) on the shoulders.
The arms are completely relaxed at the side to start.
This starting position is used in many qigong (chi kung) or internal arts to start your form. This will bring you into a relaxed state and allow the qi (chi) to flow freely.
When inhaling, inhale only through the nose. When exhaling, exhale through the nose and or the mouth. I usually suggest to only exhale through the nose as we tend to exhale to quickly when using the mouth. Your inhale and exhale should be even in duration. The minimum you should be seeking is at least 4 seconds to inhale and for seconds to exhale.
The tongue should be lightly pressed to the roof of the mouth.
As you inhale, the stomach should extend outward, as you exhale pull inward. Your breath should be slow, even, and comfortable. This is considered natural breathing. This the method we use when we are born into this world.
Above writing from this website.
I like to this lying down for meditation with the focus on your middle dantien, which is is a qi storage area in the center of the body near your navel.