Piglet: nothing much to prepare actually. U hv to trust and have faith - important. (Last time someone went with all negative thoughts, and keep asking why no success, my shifu ask her to go home and think abt it, and if ready then come back. Later she went back to shifuand shortly conceived.
If u going at night like 7pm like me, rem to hv dinner if not hungry later as session may stretch to 2 hrs..
Ching: It's up to you actually. Are you exercising regularly now? If u r, perhaps it's not necessary to attend yoga. I went for yoga cos I'm din hv any form of exercise at that time. I went for mon n fri classes. Mdm tan slows down her classes for newbies so no worries abt catching up. Hope this helps. Let me know if any queries