My teachers are making me an offer that is hard to refuse. They will give me free constructive criticism on my teaching for the next level, Junior Intermediate I. The JI1 syllabus is rife with arm balances. In Iyengar yoga, it’s not just one thing to be able to have complete competency in doing the pose. That’s a given. You have to have complete competency in teaching the pose SAFELY to someone who has little experience or has never tried it before. That changes the way one approaches the asanas. One has to try different ways of doing the pose to make them more accessible in stages. Today, after doing an hour of standing poses, I worked on Adho Mukha Vrksasana (Downward Facing Tree Pose) and Pincha Mayurasana (Tail Feather of the Peacock Pose).
A nice way to approach poses that counter gravity is to first try the actions of the poses taking gravity out of the equation. Here is how I worked the arms and the chest for Adho Mukha Vrksasana.
I used a wall for Tadasana, and extended my arms to urdvha hastasana. The second action was lying on a block with the far edge at the corner of my C7 and T1 and pressing my hands against the wall. This creates a tremendous opening in the chest. 
I would not recommend this pose for beginners until you can do Gomukhasana arms without a strap as seen above.
Next, I used wall ropes to take the weight out of the wrists. 
Now I try the pose kicking up to a wall with the hand rotated to the side which is the final version for the JI1 syllabus.
I give Pincha Mayurasana a similar treatment.
I wanted to finish my practice with Supta Baddhakonasana (Reclined Bound Angle Pose). I normally practice with a strap, but today I experimented with a blanket which presses the soles of the feet completely together giving a different effect to the groins. 
And then I tried classic Supta Baddhakonasana. I was inspired by a blogger earlier today who was lamenting about the use of props in yoga practice. Note there are no props with this variation.
The genius of BKS Iyengar is his ability to take the classic pose apart, work on the individual pieces, then put the pose back together. He did this through experimentation with props. Very few would argue that he does not teach “real yoga.”
The advantage of home practice versus taking yoga in a class, is you have the time to experiment with concepts you are curious about. I would advise to experiment within the scope of your ability.
Home Yoga Practice 