First, to practice sitting, you need a quiet place. Use a thick mat, and do not let in smoke or drafts. Keep out the damp.
The place for sitting should be carefully and properly maintained. It should be warm, and not too dark in day or night. In winter it should be heated, and in summer it should be pleasantly cool. Leave behind all attachments and bonds, and keep yourself entirely at rest.
Do not dwell on thoughts of good things or bad. Sitting is neither contemplation nor meditation. Do not think of it as a means for attaining enlightenment. Rid yourself of superficial notions of sitting and lying down. Eat and drink in moderation. Use your time well, and do not waste it. Like one whose hair is on fire, make use of every moment, sitting down quickly and devoting yourself to the practice. When you practice sitting, wear a mantle and use a cushion. Don’t sit on the entire cushion but only on the front, placing it under your buttocks.
This is the way of sitting that has been passed down from buddha to buddha and from ancestor to ancestor.
There are two ways of sitting, the full lotus and the half lotus position. In the full lotus, the right foot is placed on the left thigh and the left foot on the right thigh. The soles of the feet should be laid horizontally on the thighs, in perfect symmetry. In the half lotus only the left foot is placed on the right thigh.
Wear your robes loosely and sit up straight. Next, put your right hand on your left foot, your left hand in your right palm. The tips of your thumbs should be touching. Hold your hands close to your body. Hold yourself erect as you sit. Do not lean to the left or right, and do not bend forward or backward. The ears should stay even with the shoulders, and the nose and the navel should be aligned. Hold your tongue against the roof of your mouth. Breathe through the nose and keep your teeth and lips together. The eyes should be open, neither too wide nor too narrow. When you are ready to begin, take a deep breath. Sitting this way, you become immovable. Surpassing existence and nonexistence, you free yourself from constrictions of thought. This is the way of Zen sitting.
Early morning sitting lasts normally for a single session of forty minutes, the length of time it takes for one stick of incense to burn down.
Eat Sleep Sit : My Year at Japan's Most Rigorous Zen Temple by Kaoru Nonomura, Juliet Winters Carpenter