There is a special type of concentrative meditation which is known as 'Chakra meditation'. In essence, this is Kundalini yoga -- the practice of causing psychic energy (kundalini) to flow upward energizing the various chakras along the way. The technique is very simple and will eventually produce powerful results but patience is necessary. As each chakra is activated and energized by this practice, it is believed that increased psychic and astral abilities will result until at last the crown chakra is reached. With this, full enlightenment is attained. With some kundalini awakens all by itself but the vast majority must diligently worked at it.
To practice this chakra meditation, you simply need to concentrate on the chakras, beginning with the root chakra, and moving progressively upward. See the listing of Chakra attributes for correspondances to assist in this. Focus on each center as you visualize them opening and your psychic energy traveling upward from the root chakra opening and energizing each higher chakra. As mentioned, each chakra has certain properties associated with it, so that this type of visualization will raise your overall consciousness, promote astral projection as well as a greater awareness of your spiritual self.
It is favorable to get into a daily routine for your meditations if at all possible. Ideally, 15 to 30 minutes a day is adequate, but by all means, find what works best for you. Naturally, being in good physical condition and having flexability is very helpful too. Diet will also play a vital role. If you are a fast food junkie and or couch potato don't expect noticable results.
You will know if you are achieving results because you will either feel light tingling vibration or buzzing sensations or a sensation of warmth and possibly a light throbbing in the chakras.
There are numerous forms of meditation and each has their own specifc traits and goals. While we can offer suggestions and guidelines, it will be necessary for you to research and study the various methods combining this with experimentation to discover which works best for you.