Kriya yoga is considered to be an advanced technique which is geared for the awakening of the psychic centres and the creative energy in the form of the inherent kundalini, which lies dormant in every individual. Prior to the practice of kriya yoga, there has to be mastery over other yogas such as hatha yoga and the cleansing practices or shatkarmas. The body should have attained a certain degree of purification. One has to be aware of the pranic flow within the body, of the chakra system, and how the chakras influence the various manifestations of the personality.
One must be able to practise the techniques of raja yoga as well as have a certain amount of control over the body: the ability to sit in a particular posture for a certain length of time, and to retain the breath in order to create physiological changes in the cardiovascular, respiratory, muscular and endocrinal systems. The ability to convert the normal parameters through the practice of pranayama and asana must be achieved. There also has to be an understanding of the various practices for the awakening of the mental faculties, the techniques of pratyahara, dharana and dhyana. Unless and until we understand the processes of hatha and raja yoga, it is not advisable to go deeply into the kriya yoga practices.
Often in kriya yoga we encounter psychic experiences which alter our perception of the body, and which change our behaviour, affect our emotions and make us more sensitive.
If we are surrounded by some kind of positive or negative influences and we do not know how to observe them, but dwell in the experiences of those emotions, it can restrict our growth and the awakening of the chakras and kundalini.
Anybody can practise kriya yoga. Everyone is entitled to awaken the kundalini and the chakras, but there has to be a basic understanding of the hatha and raja yoga techniques. After that the process becomes much easier as kriya yoga is a combination of many techniques which have evolved through the experiences of the awakening of prana, of lifetimes of karmas and samskaras, and of the awakening of kundalini.