Etiquette is not a loud and explicit rule; it is soft and subtle and yet always carries you further when you observe appropriate etiquette in the right setting. Yoga, which everyone can do, is no exception. A tradition as ancient and beautiful as yoga comes with a certain level of implied etiquette and it is the sincere hope of any devoted yoga practitioner to see all his or her fellow yogis observe the same unwritten proprieties.
Respect Other's Space - Keep your mats evenly spaced, and stagger rows. Keep water bottles and towels close to your mat. Leave what you don't need for your practice in the cubbies.
Take time to enjoy the Final Savasana - For someone who is not familiar with yoga, the last few minutes can seem unimportant and optional. This is not the case, it is actually the most important part of your practice. When you are ready to leave, do so quietly. Rolling up of your mat and towel can be done outside of the yoga room. The hand/face towel are not to be used to clean your mats. If you are unsure of when/where/how to clean your mat, please don't hesitate to ask. Some like to stay in Final Savasana a little extra long, so please be aware of the ripple effects your actions may have.
Consider the overall atmosphere of the class - The sounds of cell phones and watches, running commentary with your friends and intense grunting can be distracting to your fellow yogis, so try to keep any excess noise to a minimum during class. A loud exhale, excited squeal, or occasional giggle is completely normal. Just be mindful of the impact you are having on the others in class.
Avoid leaving the yoga room during class if at all possible - A good rule of thumb to follow: if you don't want to leave the room but have to (ex. emergency or bathroom) then it is ok to leave the room. If you want to leave the room (ex. get more water, need air, frustrated) then it's not the best idea to leave the room. The teacher can help you with those needs much better when you are in the room.