"The Way is basically perfect and all-pervading. ….And yet, if there is a hairsbreadth deviation, it is like the gap between heaven and earth. If the least like or dislike arises, the mind is lost in confusion.

Therefore, put aside the intellectual practice of investigating words and chasing phrases, and learn to take the backward step that turns the light and shines it inward...

If you want to realize just this, get to work on just this right now.”

For practicing Zen, a quiet room is suitable.
Put aside all involvements and let the myriad things rest.
Do not think good or bad. Do not judge true or false.
Give up the operations of mind, intellect, consciousness; stop measuring with thoughts, ideas, and views.
At your sitting place, spread out a thick mat and put a cushion on it.
Sit either in the full lotus or half lotus position….[or kneel, or sit erect in a chair]
Then place your hands on your lap, left hand on your right palm, thumb-tips lightly touching.
Straighten your body and sit upright, leaning neither left nor right, neither forward nor backward.
Align your ears with your shoulders and your nose with your navel.
Rest the tip of your tongue against the front of the roof of your mouth, with teeth and lips together.
Keep your eyes open. Breathe softly through your nose.
Once you have adjusted your posture, take a breath and exhale fully.
Rock your body right and left, and settle into steady, immovable sitting.

        Think not-thinking.
        How do you think not-thinking?
            Non-thinking - beyond thinking.
        This is the essential art of zazen.

When you arise from sitting, move slowly and quietly, calmly and deliberately. Do not rise suddenly or abruptly.

The zazen I speak of is not meditation practice. It is simply the Dharma gate of great ease, peace and joy:
Zazen Tips - Shikantaza (“Just Sitting”)
Place a zabuton with the zafu on it in front of a wall. Then sit facing the wall in one of the following ways:
Pasted Graphic Half-lotus position: Place the base of your spine towards the front of the zafu. Sit with your left foot on your right thigh. When you cross your legs, your knees and the base of your spine form a triangle. For full lotus, also place right foot on left thigh; toes of each foot should align with outer edge of thigh.

Burmese Position: Sit with your left leg in front of the right or vice versa, resting on a zabuton

Pasted Graphic 1 Seiza: Sit on your knees supported by a seiza bench, or sitting on a firm zafu.

Pasted Graphic 2 Chair: Use a good straight, armless chair. Sit upright, not leaning back. Use a support cushion or zafu to support your upright posture.

Pasted Graphic 3Swaying the body
Place your hands palms-up on your knees and sway the upper half of your body from left to right a few times. Without moving your hips, move the trunk so that the waist and hip muscles are stretched. You may also sway forward and backward. At first this movement should be large, gradually becoming smaller and smaller, and ceasing with your body centered in an upright position.
First breaths
Quietly make a deep inhalation. Slightly open your mouth; exhale smoothly and very slowly. In order to expel all the air from your lungs, exhale from the abdomen. Then close your mouth and place the tongue lightly against the roof of your mouth, just behind your teeth. Continue to breathe through your nose naturally with the mouth closed but relaxed.

Pasted Graphic 4Zazen Posture
Rest both knees firmly on the zabuton, straighten the lower part of your back, push your buttocks outward and hips forward, and straighten your spine. Pull in your chin slightly and extend your neck as though reaching toward the ceiling. Ears should be in line parallel with your shoulders, and your nose in line with your navel. Relax your shoulders, back, and abdomen. Sit upright and be flexible, leaning neither to the left nor right, neither forward nor backward. Once established in your posture, do not move.

Pasted Graphic 5Eyes
Keep your eyes slightly open. Cast them downward at about a 45' angle. Without focusing on any particular thing, let everything have its place in your field of vision.
Pasted Graphic 6Cosmic Mudra
Place your left hand palm-up on your right palm. The tips of your thumbs should be lightly touching each other. Place your mudra roughly in front of your navel, arms slightly apart from your body.

Abdominal breathing
During zazen, breathe silently through your nose. Do not try to control your breathing. Let it come and go so naturally that you forget you are breathing. Let long breaths be long, and short breaths be short.

Do not concentrate on any particular object or control your thought. When you maintain a proper posture and your breathing settles down, your mind will naturally become tranquil. When various thoughts arise in your mind, do not become caught up by them or struggle with them; neither pursue nor try to escape from them. Just leave thoughts alone, allowing them to come up and go away freely. The essential thing in doing zazen is to awaken from distraction and dullness, returning moment by moment to posture and breath, without any judgment or notion of success or failure.