There are countless schools of meditation out there and each with their own systems of breathing, posture, and movement. But most of the methods of meditation can be reduced to two major categories, mindfulness meditation and concentration meditation. The former is conducive to finding inner peace, and the latter promotes internal energy development.
Mindfulness meditation is designed to reunite us with the present. Many conceive of meditation as escape or transcendence of reality, and this couldn't be further from the truth. Mindfulness meditation is not escape from reality, but is a return to it. Day in and day out we are looking forward or looking back. We're thinking about our day at work, we're anticipating our Friday night date. We rarely experience the fullness of our present reality, because our minds are preoccupied.
By discarding our normally ego driven habits for a few minutes of silence we can open ourselves up to the power of now. There is no need for formality in mindfulness meditation. You can walk, eat, or sit silently and observe, listen, smell, feel, taste, and even watch your own thoughts without judgment. Your mind may wander and that's ok, continue to be aware and watch it. As you watch your thoughts you'll find they disappear and your attention returns to your present reality, both internally and externally.
The simplest way to approach mindfulness meditation is through sitting meditation. You can do this anywhere and at anytime, though perhaps it's easiest in a quiet natural place with few distractions. Your posture should be good, your breath long and steady, and your limbs relaxed. You needn't force yourself to focus on this or that or tune out your thoughts, simply observe. Listen carefully both to your environment and within yourself. Don't judge. Peace comes with living in the moment.
The other category of meditation is concentration meditation. This type of meditation is suitable for developing internal energy, as well as manipulating that energy for healing or in the case of martial arts, hurting. Concentration meditation is more formal, and requires internal focus to the exclusion of other sensations, thus the term concentration. It begins with breathing meditation, where the breath is drawn down deep to a point a couple inches below the belly button and a couple inches into the body. This is the seat of energy in the body.
To practice this meditation, ones posture should likewise be good, with a straight back, head slightly tilted forward, arms relaxed and resting in ones lap if seated, and the tip of the tongue pressed to the roof of the mouth behind the palate. Touching the tongue to the roof of the mouth connects the two major meridian lines along the front and back of the body and allows energy to circulate smoothly. Then one should breathe deeply to the lower abdomen and breathe out slowly, focusing mentally on that point the whole time.
If you reach a point where you feel a swirling sensation in the lower abdomen or heat then you're ready to circulate this energy down to the sphincter and up along the spine, over the top of the head and back out through the mouth. The first stage may take a few months to a year of steady practice; the second stage may take about the same, depending on your own sensitivity to your energy. The ability to circulate ones energy is the foundation for sound health and later, the ability to heal others by channeling this energy through the arms and projecting it outward.