Raise the arm(s) over the head on the inhalation, raise the legs on the exhalation
Hold each posture for three to six breaths
Ideally we want to keep the sacrum, the small of the back on the mat while lifting the legs, difficult, engage mula bandha to anchor.
Suptapadangustasana pic. 6 & 7 is another vinyasa found in Ramaswami's Yoga for the three stages of life.
After raising the arm above the head and again when lowering the leg we take a couple of breaths to really stretch the leg and arm on the same side or across the body on opposite sides.
When raising the leg we begin the lift at the buttock, the hip joint rather than just with the foot and lower portion of the leg.
Stretch through the whole length of the arm and leg when lifting and lowering.
On lowering both arm and both legs, another vinyasa is to hold for a breath at 45 degrees.
In the final posture, suptaparsvapadangustasana (pic.11), spreading the legs and lowering as far as possible try to drop the femur heads in the hips socket which is really dropping the sacrum back towards the mat rather than just pulling out and down on the toes.
Work towards suptaparsvapadangustasana (pic.11) by working on the parasarita series from the triangle sequence along with trikonsasna from the same series and the upavishta trikonasana from the seated sequence.
The leg lifts are basically forward folds/bends, as such they can involve an intense hamstring stretch, be sure you are sufficiently warmed up, perhaps through some of the standing postures. Alternatively, work in to these stretches by raising the leg only half way for the first couple of breaths, going a little deeper with each vinyasa.