Meditation
Meditation even in different schools of Zen is a little different. So in Japan (Soto and Rinzai schools) focus is mainly on posture and breathing, while the school Choge (Korean tradition) focuses on the state of mind. I myself was educated at the School of Kwan Um School of Zen relating to the Order Choge, and what I will talk about techniques of meditation is taken from personal experience.
About how to sit in Zen meditation, you can read the excellent article Sekida Katsuko "The practice of Zen" on page LIBRARY. There's even a pictures. Therefore, let us talk about how to "sit" intelligence during meditation.
First of all, do not fight with your thoughts, do not try to stop them or do something to influence them, for to stop your thoughts you you will use other thoughts. Thoughts come and go like clouds in the sky. If you do not pay attention to them, they are gradually depleted and the mind becomes pure. It's like a glass of troubled water. If you do not touch the glass, haze settles and the water is purified. Thoughts feed on our attention to them. As soon as we estimate some of them (on a scale of "bad-good," "like-dislike," "want-not want"), they immediately took all our attention, and riding them, in a moment we are flying somewhere very far from the hall of meditation.
During the Zen meditation we do not close our eyes, as with closed eyes creative thinking turns on (pictures appear). To make automatic thinking less distracting, lower the eyelids leaving only slits. Just look all the sculptures and illustrations of the Buddha in meditation. His eyes are almost closed.
If, however, during meditation, you begin feeling too sleepy, open your eyes wider.
There are many methods ("spikes") to help at first not to fly away in your thoughts during meditation. You can recite the mantra. You can follow the breath, counting exhalations. One, two, three ... up to ten. Then again to ten, and again to ten, etc. Once you start to consider "eleven, twelve ...", it means you are already asleep.
Another very good way to keep your mind focused and calm:
Our hands during Zen meditation closed in a mudra on the point located two fingers below the navel. This is the center of our physical body, the center of the primary energy and the center of intuition. If you focus on this point, then after a while you can "hear" (feel) there the pulse of heart. At first just watch it, and when it becomes clearer, start following its blows to repeat some mantra. For example: "GA-GA-TE-TE-PA-RA-GA-TE-PA-PA-SAM-GA-TE-BOD-HI-SWA-HA.
While your mind is busy repeating the mantra, exhales count, or tracking puls rate, pay attention to the fact that you are awair of that. What makes the mind, watch for its activities.How do you follow? Who monitors if your mind is busy? Who are you? THIS IS VERY IMPORTANT!