The legs are crossed in the vajra posture. This helps to reduce thoughts and feelings of desirous attachment.
The right hand is placed in the left hand, palms upwards, with the tips of the thumbs slightly raised and gently touching. The hands are held about four fingers' width below the navel. This helps us to develop good concentration. The right hand symbolizes method and the left hand symbolizes wisdom—the two together symbolize the union of method and wisdom. The two thumbs at the level of the navel symbolize the blazing of inner fire.
The back is straight but not tense. This helps us to develop and maintain a clear mind, and it allows the subtle energy winds to flow freely.
The lips and teeth are held as usual, but the tongue touches against the back of the upper teeth. This prevents excessive salivation while also preventing our mouth from becoming too dry.
The head is tipped a little forward with the chin slightly tucked in so that the eyes are cast down. This helps prevent mental excitement.
The eyes are neither wide open nor completely closed, but remain half open and gaze down along the line of the nose. If the eyes are wide open we are likely to develop mental excitement and if they are closed we are likely to develop mental sinking.
The shoulders are level and the elbows are held slightly away from the sides to let air circulate.
Kamalashila: Stages of Meditation
Then, they should seat themselves on a comfortable seat, either in the full lotus posture of Vairochana or the half-lotus posture.
Their eyes should not be open too wide, nor too tightly closed, but focused on the tip of the nose.
Their body should not be bent forward or backward, but kept straight, and their attention turned inwards.
Their shoulders should rest evenly, and the head should not be tilted back or forward or to either side.
The nose should be in line with the navel.
The teeth and lips should rest in their natural state, and the tongue should touch the upper palate. Inhalation and exhalation should be just barely discernable, gentle, soft and natural, without undue noise, effort or agitation.