There's an interesting article in the Huffington Post today about what a yoga teacher learned in her teacher-training classes.
Author Valerie Reiss frames the article in terms of the lessons she herself learned about life, but the article can also be read in a different way: it's a primer for yoga students on how a good yoga teacher should treat you.
1. A good yoga teacher should emphasize how important breathing is. Reiss talks about attending fast-paced, strenuous vinyasa classes where the breath was all but ignored. Not only does paying attention to the breath bring you back into the moment, says Reiss, and stop your mind from wandering onto your worries, but it also makes you more aware of how your body's feeling. That, in turn, makes you less likely to injure yourself. A good yoga teacher should keep bringing you back to the breath.
2. You shouldn't feel like your yoga teacher is pawing at you, or, conversely, trying to yank you into the correct pose. Reiss says one of her instructors told the class, "Don't 'pet' your students." There should be a clearly observed line between helpful touching and physical contact that makes you feel uncomfortable or causes you pain. Also, your teachers should know about the proper way to assist you in a pose - that's something they should have learned in training.
3. A good yoga teacher should know that even the most accomplished and flexible students have physical limits that they literally cannot go beyond. For example, Reiss says, certain students may never be able to do a headstand without it hurting, because the length ratio of their arms to their neck might, quite simply, prevent them from doing so. That's due to their skeletal structure, not because they need to "relax a little more," or "try a little harder." Instructors should consider this as a possibility rather than attempting to assist that particular student or encouraging them to go deeper.
4. It's always OK to use props - a good yoga teacher should never make you feel weak for wanting to use a block or a strap. If you need an extra bit of help, that just means you're listening to your body, rather than potentially pushing it to injury. Your teacher should always encourage you to pay attention to your physical cues.
Reiss makes many more good points in her article, which can be found here.