A not oft discussed, yet vital aspect of yogic practice involves preliminary cleansing.
In Tantric kundalini practices the sadhaka (practitioner) clears the central channel known as the shushumna, in order for the coiled serpent energy known as the kundalini to arise and activate in the sahasrara or crown chakra. Though it is activated in the muladhara (root) chakra it is said to be only ignited there from to its actual resting place in the crown. The symbol is like a reversed tree with the roots resting in the crown or head. A fully activated kundalini leads Shakti to Shiva (animate force to consciousness; divine union; samadhi).
Many have heard of the frightening ‘Kundalini Awakening’ stories where one can experience extreme states of overheating, blacking out, hallucinations and feeling painfully out of control with ones own body and senses. (I must also add that having one of these partial awakening experiences is not an indication of having a fully awakened kundalini, as to have a fully awakened kundalini would mean to have reached full self-realization).
Beware of the spiritual egotism that arises when one first senses the power of a rising kundalini and then hastily and impatiently rushes ahead without proper guidance.
While such experiences are rare and are carefully avoided through a proper guru/teacher, they usually occur when the kundalini rises and strikes against impurities in a combustive energetic explosion.
What is occurring in neurotic and psychotic states of an overactive kundalini is not a fault of kundalini energy, only a result of a sudden onset and stimulation of what was already dormant within.
To avoid any such unpleasant experiences, a yogic sadhana (practice) should be predated by a proper series of cleansing rites. A clear mind, strong clair-focused willpower, and a purified body will lead to a much more graceful ascent of the goddess kundalini.
Cleansing can include purificatory mantras (sacred words), pranayamas (breath), and specific asanas (postures).
In classical Hatha yoga there are 6 shatkarmas which can also greatly help in clearing the nadis (energy channels) and the central path of the shushumna:
Purifying the nostrils and air passages
Cleansing of internal passages, including digestive and respiratory tracts
Stimulating digestive fire
Clearing out the colon
Cleansing the respiratory system through powerful exhalations
Internal and external eye gazing practices to steady the mind