Position, props, and partners can all assist you in breath-work.
1. Supine Position
The basic techniques of pranayama are best learned lying down; you won't be distracted by the challenge of maintaining a stable, upright, seated posture, and you can use a bolster to help expand your chest. Fold a blanket into a bolster—about 3 inches thick, 5 inches wide, and 30 inches long. Use a second blanket to form a thin pillow and lie back so the thin bolster supports your spine from just above your sacrum to the top of your head.
2. Seated Position
The optimal position for pranayama is a simple seated meditative pose—Sukhasana, Siddhasana, or Half or Full Lotus Pose—with the addition of jalandhara bandha, the chin or throat lock. To perform jalandhara bandha, raise the top of your sternum toward your chin, tuck the hinge of your jaw toward your inner ear, and softly lower your chin toward your sternum.
In pranayama you strive to distribute your breath evenly throughout your entire lungs—top and bottom, left and right, front and back. At first, you may have a hard time sensing the parts of your lungs that aren't opening; a gentle, steady touch (and verbal feedback) from a yoga buddy can increase your awareness and help you learn to breathe fully and evenly.
You can use props to help you sense where your lungs may not be expanding fully. Belts cinched snugly around your rib cage—one up near the collarbones and one around your floating ribs—will quickly show you which parts of your lungs you tend to neglect. You can also bring awareness to the contact between your back and your bolster to see whether you tend to breathe more with the upper or lower portions of your back lungs.