Preparation for Pranayama 

As people have attraction towards Yogasanas, similarly they have attraction and also perhaps, a sort of awe towards Pranayama. The process of Pranayama is concerned with the breathing, the indicator of life. And therefore, if it is done wrongly, it may do harm to the person. This fear dissuades many from taking up Pranayama. But, if it is learnt and practiced under an expert's guidance, one learns soon and experiences its wonderful  benefits.

In Patanjali's "Ashtanga Yoga", Pranayama appears at the fourth stage. This means unless one observes Yama-Niyama and does Asanas well, one cannot reach this fourth stage. Even after learning these Asanas and having practiced them, one needs some preparation before actually taking up Pranayama. 

The breathing process chiefly involves two activities, viz., inhaling and exhaling. The former is called "Puraka" and the latter "Rechaka"' in Yogashastra. These two activities continue non-stop right from the birth to the death of a person. The state when these two activities are deliberately made to halt for some time during Pranayama is given the name "Kumbhaka". The halt after inhaling,  is called "Abhyantara Kumbhaka" and that after exhaling is called "Bahya Kumbhaka". 

Breathing itself may be classified under three categories:  
Quiet Breathing:  the smooth breathing that continues naturally without any effort.
Deep Breathing: the protracted breathing which is caused by deliberate slowing down of the breathing. 
Fast Breathing: the quick breathing which is caused by deliberate increase in the speed of breathing.  

Pranava Mudra

In Pranayama, the breathing is controlled with the help of the right hand which is held in Pranava Mudra. For this mudra, the first two fingers after the thumb are bent and last two fingers kept straight and held together; the thumb is held straight. Bending the right hand at the elbow, place the bent two fingers near the lips. Keep the hand from shoulder to elbow close to the chest. Keep the right hand thumb on the right side of the nose and last two fingers on the left side of the nose. The right nostril can be closed by pressing the thumb and the left nostril by pressing the last two fingers. The pressure should be light and on just below the nasal bone, where the fleshy part begins. There should be only the movement of thumb and the last two fingers. Movement of other parts should be avoided; the face should be kept calm and relaxed.  While practicing tPranayama one should first sit in one of the following Asanas: Padmasana, Vajrasana or Swastikasana. The left hand should be held in Dhyana Mudra and the right hand in Pranava Mudra. The eyes should be closed and the mind's attention should be concentrated on breathing without any distraction.

Type - 1 Keeping both the nostrils open, inhale and exhale with as much speed as possible and for as much time as feasible.

Type - 2 Close the right nostril with the the thumb of the right hand held in Pranava Mudra, and inhale through left nostril and then exhale through the left nostril. In brief this type can be described as quick breathing with the left nostril.

Type - 3 In this type left nostril is to be closed and the quick breathing is done through the right nostril.

Type - 4 In this type close the right nostril, and inhale with the left nostril, and then immediately close left nostril and exhale with the right nostril. 

Type - 5 This type of breathing is just opposite the previous one, that is, the left nostril is closed and inhaling is done with the right nostril, then immediately closing the right nostril, exhaling is done with the left nostril.

Type - 6 This type of breathing combines previous two types: First inhale with left nostril and exhale with right one, then inhale with right nostril and exhale with left nostril. Later continue the same process i.e. inhaling & exhaling with left and right nostrils alternately. Further switch to fast breathing by increasing the speed of breathing.