Each soul is potentially divine. Meditation helps to acquire purity of mind to manifest this divinity within. Realization of our true divine nature is the goal of human birth.
The term meditation is used in relation to controlling and disciplining the mind by yoga practices. In Patanjali's Yoga Aphorisms, out of eight-fold procedures, meditation forms last but one step. Before meditation comes concentration, and after it is the final transcendental state of samadhi. Other injunctions that are to be followed are a) to lead an ethical and simple life, b) to undertake some breathing exercises to control prana and, c) to withdraw sense organs from their objects.
It is said that all these requisite practices fall in aspirant's stride once he takes to practice of meditation. Therefore, there is no need to brood over our moral weaknesses, even if any.
The states of 1) concentration, 2) meditation, and 3) samadhi are the source of all knowledge and bliss. Knowledge in every field of activity has been initially revealed to some persons who had reached such meditative states, and has thence reached over centuries to humanity in general.
Following are general guidelines for meditation. The procedure and effort is harmless, but requires honest, sincere, sustained, and prolonged practice over many months and years for any result to become visible.
(1) It is preferable to lead pure and simple life as far as possible. Food should be small in quantity at a time, and meat, alcohol, and smoking is best avoided. Adequate sleep is necessary. Virtues such as truthfulness, continence, non-injuring others by words or deeds, and prayerful attitude are helpful. (It is not possible to give up meat, alcohol, smoking, and sex abruptly. But the quantity and frequency can be reduced.)
Try and cut down a few unnecessary desires and requirements.
Perform one selfless act daily, or at least once a week. Such act as helping old person cross road, nursing the sick, or feeding the invalid. Even allowing someone to overtake you on a highway will do!
(2) The best time for meditation is early morning and evening when nature is tranquil and quiet. Twice a day practice is preferred but morning meditation alone is quite sufficient to begin with.
(3) It is preferable to take shower before sitting for meditation. Clothes should be light and loose, preferably cotton. It is better not to eat anything before meditation, but exception can be made for a cup or glass of water or fruit juice.
(4) It is better to decide before the start of practice the object of meditation. A spiritual teacher best suggests this, but for want of the same, one can choose the form of one's liking and inclination.
For instance, one may meditate on a form of one's chosen ideal such as Christ, Cross, Church, Buddha, Sri Ramakrishna, Sri Krishna, Rama, Shiva, or Kali, or any revered Prophet or Holy person of his or her religion.
If this is not desirable or one's constitution does not approve of meditation with form, one may choose vastness of sky or the ocean as the object of meditation. Or else, pure formless meditation can be attempted that includes meditation on a thought or an idea of Absolute Beauty, Bliss, Ethics, etc.
(5) To begin with, choose a quiet room or a corner of any room as the place for meditation. Install a photo or image of your chosen ideal or the symbol, if you have decided to meditate with form.
Sit cross-legged on a small mattress (2 feet by 3 feet) in a comfortable posture that allows you to be stable with least movements for some time, say 30 minutes.
Spine and the back should be held straight.
(6) You may light incense stick and/or offer flowers to your chosen ideal who is symbolized in the form of a photo or image or an idol.
(7) Then close your eyes and pray for the welfare of all. Like, pray, 'let all noble thoughts come me from all over the universe. Let there be peace and bliss all around. Let all beings be joyful and happy'.
(8) Now, think of pure space in the region of your heart. Imagine that it is all peaceful, vast, and effulgent. The light is cool and blissful. Those who meditate with form should think that the effulgence is in the form a lotus with eight petals. In the center of this illumined lotus there is another blissful effulgent form of their chosen deity or symbol. Those who practice meditation without form should think of uniform blissful effulgence.
(9) Gradually think and imagine that the light is spreading all around and occupying the inside of thoracic cavity. It is filling chest inside. Continue to see this effulgence spreading to abdominal cavity reaching towards thighs, legs, and feet.
(10) Think of the similar spread to shoulders, arms, hands, head, neck, and face.
(11) Now your whole is filled with radiant blissful light.
(12) Next, imagine this effulgence spreading outside your body; above your head, below your seat, to the right and left, and in front and back. From all side this wonderful calming effulgence surrounds you.
(13) Continue as long as you can. Initially the mind will rebel. Various unthinkable thoughts will crowd your mind. The thoughts of lust, hatred, cruelty, thoughts regarding your office or home, wife (or husband, or friend), children, past experiences, etc. will spring up from no where. This all may frighten you. The best course is to ignore these thoughts. Just observe them as a witness. Do not fight them. Gradually with perseverance over a period of many weeks their power will wane.
(14) Continue to sit in a relaxed frame of mind for five to ten minutes before you leave the room. During this period you may say prayers, sing a song in the praise of the Lord, or read some good text from the Scripture or a Holy Book.
(15) Do the same practice everyday about same appointed hour on the same mattress. Do not use that mattress for any other purpose. It is best to switch off your mobile phone etc. However, do not get irritated if visitors ring the door bell or the phone rings abruptly. Take it as a divine interruption, and accept all the weaknesses of self and others as natural.
(16) Initially one may become slightly more irritable, but within a few weeks you start feeling better in your body and mind. But mental tranquility and physical fitness are not the goal of meditation. These are just good side effects. The goal is to get glimpses of our true nature, that is Divinity. It takes about three years of regular practice for the desired results to become visible.
(17) To start with, meditate for five minutes in the morning and five minutes in the evening, or ten minutes in the morning or evening as suits you. When the posture becomes comfortable and mind becomes steady, gradually increase the duration.
(18) You can always skip the meditation if you do not feel so on any particular day, or if you are mentally not prepared. Anxiety and stress on account of meditation is not normal. In such situations you should just do prayer and worship.