Path of Devotion (Bhakti-yoga):
The path of devotion aims at the enjoyment of the supreme Love and Bliss. It focuses on realization of Truth (true reality, true potential) through means of devotion and surrender. Prayers, rituals, and ceremonial processes are its basic approach. Chanting, singing, and repeating God's name are also important practices. In the initial stage of spiritual progress, a temple or similar place is needed to practice Bhakti yoga. Ultimately, Bhakti yoga develops humility within and dissolves ego or I ness. This is an excellent form of yoga for emotionally oriented people.
Path of Knowledge (Jnan-yoga):
The path of knowledge aims at the realization of the unique and supreme SELF. Intellectually oriented people prefer this path because it uses study, thinking, direct inquiry, and contemplation as its practices. This path is typified by spiritual discrimination between what is real (true reality) and what is unreal or illusion (Maya) in the universe.
The path of action aims at the dedication of every human activity to the supreme Will. It is the yoga of action and selfless service for the benefit of humanity at large. This includes social work, ecology, environmental protection, education, animal protection and the like. It can be practiced anywhere at any time. Ultimately the person dedicates all Works and Services as an offering to God, without any expectation of results or personal gain. This dissolves one's ego or I ness. This is an excellent form of yoga for action oriented people.
Raja yoga aims at the liberation and perfection not only of the body, but also of the mental being, the control of the emotional and sensational life, the mastery of the whole apparatus of thought and consciousness. It is the science of physical and mental control. A great sage, Shri Patanjali, pioneered it. It is also known as Astanga yoga, or the yoga of eight steps.
In the initial stage, a person should restraint from violence, untruthfulness, non chastity, stealing, and material possessions.
In the second stage, a person should develop virtues like cleanliness (external and internal), contentment, austerity, religious study, and self surrender to God.
The first two stages are meant for moral purification, without these no spiritual progress is possible.
In the third stage, a person should do physical exercise (Hatha yoga) to keep the body healthy and the spinal cord straight in preparation for long periods of meditation (1 hour).
In the fourth stage, a person should practice regularly the control of vital energy through certain breathing techniques. Rhythmic breathing helps concentration of the mind.
Sitting still (step 3) and rhythmic breathing (step 4) makes the mind fit for looking inward.
In the fifth stage, a person should practice detachment or divorcing of mind from the five senses (touch, taste, smell, sight, and sound) which provide pleasant or unpleasant feelings. This mental exercise gradually slows the rush of thoughts from within to the surface of the mind. Now the mind has become ready for concentration on one object or on one idea.
In the sixth stage, a person should concentrate the mind either on one external object or one internal idea upon which to meditate. One finds that, in spite of the best of efforts, the mind does not remain glued to the chosen object. The object appears too hazy and there are breaks in concentration. One has to make repeated attempts during Dharana which ultimately lead to emptying all other thoughts.
The thought removal process (Dharana) leads naturally to meditation (Dhyana) in the seventh stage. Meditation is an unbroken flow of thought towards an external object or an internal idea.