What is meditation?
From a Buddhist perspective, meditation turns accepted information into experience. On the first level, its purpose is to calm mind and keep it in one place. It creates space between the experiencer and his experiences, permitting the wise to choose roles in the comedies of life and avoid its tragedies. This protective distance is most frequently achieved through awareness of one's breath or the concentration onto a Buddha form, a meditation called 'Shamatha' in Sanskrit and 'Shine' in Tibetan. Whoever can hold this state of mind in the lab situation of one's meditation, will gradually accomplish the same in daily life. This is a first step in one's development and a necessary foundation for both penetrating insight and more elaborate practices.
The second level of meditation is called 'Vipassana' in Sanskrit and 'Lhaktong' in Tibetan. Here, the meditation is formless and aims at the nature of the mind itself. By being aware without an object to be aware of, insight and understanding arise spontaneously. So meditation is the concentration of the mind and the clarity which arises from this.
Is meditation good for everybody?
Diamond Way meditations are for people who aim at enlightenment. If someone only wants to relax, other means are better suited for this purpose. Generally, meditation is for people who have enough positive impressions in their mind so that they can stand to meet with their own subconsciousness. For people with a strong mental imbalance it can be dangerous to meditate, since they tend to take their feelings and inner conditions too seriously and may experience unpleasant projections. In this case, saying mantras and trying to act in a positive way is better than starting with concentrative meditation too early. Only when one feels good without taking medication and is able to work, live on one's own and maintain relationships, it is time to start meditating.
Frequently in Tibetan Buddhism there are meditations which shouldn't be practiced without having taken Buddhist Refuge. In short, refuge gives protection and creates a connection to one's Buddha nature, or potential for enlightenment. Refuge is a connection to the teachings which lead one to enlightenment and to friends which are on the same path. In the diamond way schools of Tibetan Buddhism, Refuge also includes the Lama who gives the Refuge.
Meditation can bring very positive results to people who have the proper basis for the type of meditation they practice. If advanced meditations are tried too early and outside of the well-tested progressive system, it may not work at all and throw off ones confidence, or may result in a "white wall" state: one feels calm but rather sleepy. What we strive for is a clear awareness - sharp and clear as a diamond.
How to calm a busy mind during meditation?
If the mind is busy it's good to take a little more time focusing on the breath or form at the beginning of the meditation. If one is distracted by thoughts or emotions bring mind gently back to the focus of the meditation without judgement. This is a process of training the mind to stay in one place. Treat impractical or disturbing thoughts like a thief in an empty house. Give him nothing, let him look here and there, but not find anything. If you have a busy mind and do not attach to the thoughts which come up, there can be no harm. Don't give your thoughts any energy and you will not be bothered by them.