Here are several Pranyama techniques:

Circle Breath

This is perhaps the most fundamental of all Pranyama. It can be a part of your regular mantra or yantra meditations. Picture your breathing as a cycle, breathing in fully into your belly (yogic breath). Breath fully starting slowly (about 7 seconds for the in-breath and 7 seconds for out-breath.) Eyes closed. Speed up the breathing after about 20 minutes, so that within one hour you are taking only 2 seconds to breath in a two second for the out breath. Breathe through the nose. Do not stop at the top or bottom of your  breath.

This form of Pranyama was introduced into the United States by Leonard Orr, and is also called "rebirthing," or "conscious breathing." Holotropic, and other forms of Breathwork, are based up this form of Pranyama

Bhramari Breath

Take a deep breath, exhale all stale air from lungs, contracting abdominal muscles to squeeze out the last remnants. Inhale through the nose making a snoring sound. Retain the breath for a seven seconds concentrating on storing the pranic energy in the Manipura Chakra. Now gently exhale through the nose, making a air  sound from your palate. Focus your mind's eye on the sound during inhalation and exhalation...on the vital life force being stored and saved during breath retention. Start with seven cycles, adding more (up to 10 minutes) as you master Bhramari Breath.

Trapezoidal Breath

Start by letting  all the air out of your lungs, contracting the abdomen to help. Inhale deeply, drawing the breath toward the abdomen, expanding it, filling up your belly. Continue inhaling, next pulling into the ribcage. Continue, drawing the breath into your upper lungs, chest, and throat area. As you're breathing in, take the same seven seconds to tighten your anal sphincter.

Retain your lungs filled with prana for seven seconds. Also hold you sphincter tight for these 7 seconds.

Now begin relaxing, letting all the tension in your body release, taking seven seconds to release you sphincter. Let it be natural as you exhale slowly, taking seven seconds to release all the air in your lungs.   When all the air has been expelled, simply relax for seven seconds taking in no air.

You may wish to try this on the toilet,  releasing your bladder at the same time.

Think of this as a trapezoid 7 seconds in, 7 seconds holding, 7 seconds releasing, and 7 seconds released. The magic 28 second cycle. Do this for 10 cycles, and build up to 10 minutes at a sitting..

As well as the mental and spiritual benefits, complete breath increases oxygen supply to the blood, bring vitality to all the organs.. Complete breath also slows the heart rate. It has a calming effect on central nervous system.

Kundalini Breath

This is sometimes called Kapalabhathi, fire breath, or power breathing. It quickly energizes the body. Stand and simply breathe out in explosive breaths rapidly though the noses as if you were blowing you nose. Do it rapidly, not thinking of breathing air in. . The body will handle that. You simply breathe out  explosively. You may wish to hit your ribcage with your arms like a chicken to accentuate the out-breath. Do this for 2 minutes to start and work up to 10 minutes. As you begin, you will think it impossible to go on, but keep explosively breathing out. It will become easier as time goes on.

It is important with this form of pranayama not to take deep breaths in or you will hyperventilate and can lose physical consciousness.

Another form of this pranayama is to tighten the anal sphincter on each out breath. This works well if you are the thruster during actual intercourse.

Pranavayu Rasa

This is a recharging breath cycle. Stand with eyes closed, or turned upward, focused on the 6th Chakra, Ajna, or the third eye in middle of your forehead. Start by inhaling, holding the air in your lungs. while you swing your arms twice backward and twice forward vigorously. Then exhale. Next, inhale again, this time stretching your arms forward at a 90 degree angle from body. Swing them out sideways at shoulder level twice. Then exhale, and drop your arms.

Next,  inhale again and.swing your arms up twice and down twice, parallel at sides, arch the  small of back slightly. Exhale, and drop your arms. Now,  Inhale, keep your breath in your lungs again. Stretch arms slowly forward. Clench fists and pull them against the chest. Retain breath while shaking entire body. Exhale. Inhale again. Swing your arms overhead and bend body to the right from the waist, NOT collapsing the ribcage. Concentrate on parts being stretched. Exhale while straightening, repeat to the left. Inhale again. Retain breath, massage ribs.Exhale. Inhale. Retain breath, patting your breasts or pectoral muscles.

Finally exhale.The idea of recharging prana is to tap your individual life force and unite it with universal energy/life force. Physically, it energizes, provides limbering of physical body, cleanses and exercises the lungs.

Prana Sukha

This is a healing breath, and mean  "breath of joy" or "joyous life-force." This breath is the simplest extension of simple prana into "rhythm." Consciously alter the time spent on each part of the breathing cycle. The rhythm of Prana Sukha is said to be perfectly suited to extraction of vital energy from the atmosphere.

The Gheranda Samhita suggests: "In entering, the breath makes the sound 'SOH' and in exiting, the sound 'HAM.' Thus the breath makes the power word SOHAM; (or, I am It). The subtle sound reverberates in the root Chakra, the heart Chakra, and the third eye Chakra. The Yogi should perform this repetition consciously." Another measuring process is concentration o n a mantra, such as AUM, or whatever your personal preference. Feel the rhythm of each AUM.

Prana as Applied to Tantric Sexual Union

The above beginning prana practices should be mastered first.  They form the basis for deeper exploration into pranayama. There are many Prana breaths which apply directly to Tantric practice and Tantric lovemaking. A true follower of the Tantric path should develop complete breath until it is totally natural; then healing breath to purify the vital and subtle channels of the body.

The flows of prana, the mind, and sexual energy are interdependent. Breath control is vital to correct Tantric Union; breath is power. Fear not the power; but lean to use it carefully. Yoga and Tantric traditions believe in a five-fold division of Prana.

"The original Prana contains four other Pranas, each assigned to rule over a specific bodily function. Together, these are the five subtle breaths." The original Prana is seen as upward moving; the Apana is downward moving. These are the first and most important of the five subtle breaths. Tantra seeks to reverse the flow of Prana and Apana, then merge them, transforming the body/mind/soul. According to Krishna in the Bhagavad Gita: "Some Yogis offer the Prana into the Apana; others the Apana into the Prana." NOTE: traditionally, the Prana is considered higher, the Apana lower. Many spiritual paths have similar ideas; but in Tantric Pranayama, they are not considered "good" vs. "bad," but different flows of energy, both vital, the union of which leads to enlightenment. The Gorakasatakham (teachings of a great Indian Guru) states: "The Atman (individual soul) is in thrall to Prana and Apana. Whosoever knows and controls these two forces is a true Yogi and will taste the ecstasy of Liberation. Draw up the Apana and unite it with the Prana."

The five subtle breaths take place in prana during the period of retention. Inhale Prana, as if it were a fluid, lighter than water. During retention, see the air divide into earth, water, fire, air and ether. Exhale with fire, burning up the impurities. Pause slightly before inhalation, concentrating on impurities returning to earth for regeneration.

The Crow Beak

The very first to master prior to Tantric Union. Roll the tongue into a "beak" drawing the sides inward to form a "straw" or "tube." Protrude rolled tongue through slightly parted lips and inhale through the tongue. Retain, exhale through nostrils. This process, also referred to as Sithali  cools the body, activates liver and spleen, and strengthens the subtle pranas of sight and sound.

Union of Prana and Apana

Solar and lunar symbolism are central to Tantra, as they are to many other mystical teachings of both east and west. Most, interestingly, have similar meaning: ancient Hebrew tradition considered the sun masculine and paternal, the moon feminine and maternal; Taoist Chinese tradition considered the sun Yang/hot/masculine, the moon Yin/cool/feminine. As these beliefs developed at different times in different places, perhaps a Jungian archetypal truth is at work here.

HA: literally sun. THA: literally moon. YOGA: derived from root word "Yug," meaning Yoke. HATHA YOGA = union of sun and moon. Hatha Yoga is derived from Pranayama. The breath is linked to celestial influences; thus, when breath is controlled, the influences are controlled. The synthesis of HA and THA brings equilibrium, union, the goal of all Yogis.

Tantra associates the Sun with the right side of the body, masculine energy, the element of fire, the color red, and intellect. The solar energy is stored in the solar plexus--power Chakra--its energy is upward flowing (pranic) and considered celestial energy. The Moon is associated with the left side of the body, feminine energy, cooling (Soma) quality, the color white, the element of water and the intuitive processes. Lunar energy is stored between the Crown Chakra and Third-Eye Chakra, approximately the hairline, in a crescent-shaped portal. Its energy is downward flowing (apanic) and is considered earthly energy. The union of the two can be accomplished meditatively in Savasana with the assistance of visualization. With or without visualization, Pranayama has techniques to consciously unite HA and THA, both within the individual and within a Tantric couple, one to the other. Below are a couple of Solar/Lunar prana techniques.

Analoma-Viloma

This is alternate nostril breathing, also called Solar-Lunar Breath. It is a major key to control of sexual energy.

Solar breath = Shiva, transcendence; lunar breath = Shakti, creative energy. When both exist in balance, the life-force travels the Great Axis (spinal column), rising through the Chakras. Solar-Lunar breath employed in Tantric Union provides a thrill which impels the Atman in an evolutionary direction toward cosmic union and enlightenment. But this breath must first be controlled through the practice of white Tantra--solo, the union of HA and THA within oneself.

Technique: Sit straight in Lotus or with crossed legs, back and head straight. The rhythm may be 1:1:1 or 1:4:2, as with healing breath above. (1) Take right hand, bend index and middle fingers into palm. (2) place hand above nose. Exhale. (3) Close right nostril with right thumb. Inhale through left nostril, focusing mind on flow of air/ vital force/energy. (4) Use thumb and ring finger to pinch both nostrils closed. Retain breath. (5) Lift thumb, exhale through right nostril, keeping left nostril closed with ring finger. (6) Inhale through right nostril, focusing as above. (7) Pinch closed, retain breath. (8) Exhale through left nostril, lifting ring finger.

White, or solo HA-THA breath, has physical benefits: balancing the breath greatly assists with gaining control of parasympathetic processes such as heartbeat, circulation and body temperature. It acts as something of a natural tranquilizer, calming nerves, relieving tension, and quieting mind. Mystically, it helps the individual unite the forces within him/herself and gain ascendancy over Prana/Apana--which together equal the life force itself.

The Gheranda Samhita illustrates a meditative white Tantric form of solar/lunar breathing: "Contemplate the primordial seed sound YANG, of the air element and heart Chakra, and visualize this syllable as of a smoky color, filled with energy. Draw in the breath through the left nostril, repeating the syllable mentally sixteen times. Restrain the breath while repeating the syllable mentally 64 times, then exhale all air through the right nostril during the period required to mentally repeat the syllable YANG thirty two times."

Prana During Tantric Union

When one is ready for Tantric lovemaking, the Shiva and Shakti principles unite within themselves and each other. There is a convergence and synchronization of their breaths; life-forces merging into a vortex, physical and subtle energy exchange taking place. Lying on one side causes the opposite side's nostril to dominate the breathing pattern. The Tantras state that during lovemaking, the man should consciously draw in the exhaled air from the woman's left nostril though his right nostril, and allow her to consciously breathe in his exhaled breath from the right nostril through her left nostril. Face-to-face lovemaking with each couple lying on his/her side facilitates this exchange naturally.

One Tantric text states: "By meditating on the breath during lovemaking one should seize the life-force of the other with the life-force of oneself and bestow the life force of oneself on that of the other." During Tantric Union, the commitment of the couple is TOTAL --whether for the duration of the Act alone, for some set time limitation, for life, or for Eternity. The exchange of life forces, when done for the purpose of Tantric Commitment, binds souls together for Eternity, far transcending the Christian "till death do us part."

Final thoughts from some masters:

"The solar breath leads to transcendence; the lunar breath is a
form-giving substance. Their union evokes the Eternal."--Prana Upanisad.

"Breath is life. We should pay as much attention to it as any
other aspect of beingness"--Swami Nostradamus Virato

"When the breath is unsteady, all is unsteady; when the breath is still; all is still. Control the breath carefully. Inhalation gives strength and a controlled body; retention gives steadiness of mind and longevity; exhalation purifies
body and spirit."-- Goraksasathakam.

"The oracle of breath unfolds its secrets to those who know the keys. The elements in breath are known as fire, water, earth, air and ether."--Swara Chinthamani.

The above tactics and practices are taken from traditional sacred texts; with some commentary added by Yogini Padma Ushas Suryananda, Tantric Dancing Yogini of the Kali Yuga, and the exercises of American Tantric MAster, Swami Nostradamus Virato.