ZAZEN
The fundamental practice in Zen Buddhism, zazen is a Japanese word that literally means "sitting zen" or "sitting concentration." Yet Zazen is the experience of emptiness; it’s all about nothing. More than other methods, correct posture is paramount. Back straight. Nose in line with the navel, ears squared with shoulders, chin tucked slightly.
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Zazen instruction
From "Breath Sweeps Mind," by Jakusho Kwong, courtesy of Sounds True.

Lips are closed, teeth together, and the tip of your tongue is resting peacefully at the roof of your mouth, just behind the front teeth. This is the position the Buddha was in when he received enlightenment. Start by counting your breaths one, two…; however, if a thought intrudes upon your counting and you say to yourself, "Oh good, now I'm up to three breaths with no thinking," then you have have to go back to one since the aim is not to think about anything (because of this most beginners count "One, one, one..."). Zazen may sound hard to do with all its emphasis on discipline, but it’s the "meditator’s meditation" and will become relaxing in time. You can try it on your own but eventually you'll want to find a good teacher who'll inspire and move you more than you thought possible. Uh-oh, you're thinking again!