Sequencing Principles for Energizing and Relaxing
In practice--and especially in teaching--this will come up most with the standing poses. Virabhadrasana II (Warrior II Pose) and Ardha Chandrasana (Half Moon Pose) are examples of postures that are primarily standing poses. The latter has an element of forward bending in the standing leg, but it is still a stimulating pose. Virabhadrasana I adds an element of backbending to the standing posture, and so is even more stimulating, whereas Parsvottanasana adds a complete forward bend over one leg, which moderates the stimulating quality a bit, and Uttanasana (Standing Forward Bend) is a complete forward bend over both legs, which almost entirely balances out the stimulating quality of the standing pose, though certainly not bringing it fully to the relaxing effect of a seated forward bend like Paschimottonasana.
Once you've assessed the subtleties of the particular postures you would like to teach and determined the energetic effects they have, you can begin to construct sequences that have either a relaxing or stimulating effect, and, with this understanding, see and feel how to create balance.
To have a generally stimulating effect on one's energy, design the practice sequence to start and finish with stimulating postures, with the relaxing postures in the middle of the sequence. The Ashtanga Vinyasa Primary Series uses this design, starting with Suryanamaskar (Sun Salutes), moving into standing poses, continuing with a combination of forward bends and twists, and ending with backbends and inversions. In that system, the stimulating function is even carried out in the sequencing of the inversions themselves! Placing Salamba Sarvangasana (Supported Shoulderstand) before Salamba Sirsasana (Supported Headstand) will be more stimulating than placing Sirsasana first, as is always done in the Iyengar tradition.
For an effect that is still, on the whole, stimulating--which would be called for particularly if one is attempting to address chronic low energy levels or depression, for example--there are many other ways to approach sequencing, using the general notes above about the effects of the types of poses. For example, practice could begin with inversions--Adho Mukha Vrksasana followed by Sarvangasana and then Sirsasana--and then move into arm balances mixed with the various twists, forward bends, and standing poses from which the arm balances are derived, finishing with backbends.
When dealing with anxiety or stress, however, the ideal sequencing would start with stimulating poses and move systematically towards the most complete forward bends, and would not tend to move back and forth among types of poses a great deal as that kind of variation is actually stimulating. Longer holds in the poses will also prove helpful, as movement can also be stimulating. A sequence could start with longer holds in stimulating standing poses like Virabhadrasana I-III, then move into twisting ones like Parivrtta Parsvakonasana (Revolved Side Angle Pose) and Parivrtta Trikonasana (Revolved Triangle Pose), continue into Parsvottanasana and then Uttanasana before moving to the floor. For floorwork, start with twists--perhaps Marichyasana III (Pose Dedicated to the Sage Marichi, III), Ardha Matsyendrasana (Half Lord of the Fishes Pose), and Bharadvajasana I (Bharadvaja's Twist)--followed by progressively deeper forward bends. For the deepest relaxing effect in practice, have your student prop her head (with bolsters or blocks) during the latter third of her practice in any forward bend where her head doesn't naturally reach her leg(s) or the floor.