DO arrive early. Getting to class about 10 minutes early can help you settle in and align your attitude with the purpose of the class. While you're waiting you can practice a pose, do a few stretches, or just sit or lie quietly, breathe, and get centered. If you are late to class or if you must leave early, enter and exit the classroom quietly.
DO remove shoes before entering the practice space. Place shoes on the shelves in the lobby or in the hallway before you pass the curtains.
DO wear comfortable, non-binding clothing. Remember that at times your legs will be above your heart and you will want to keep exposure to a minimum.
DO be generous with your space and move your mat to accommodate other students. Try not to step on others' mats while setting up.
DON'T eat for two or three hours before class. If you practice yoga on a full stomach, you might experience cramps, nausea, or vomiting, especially in twists, deep forward bends, and inversions. Digesting food also takes energy that can make you lethargic.
DO let your teacher know about injuries or conditions that might affect your practice. If you are injured or tired, skip poses you can't or shouldn't do, or try a modified version.
DO create an intention. To help you focus, you might find it helpful to dedicate your practice to a certain intention. This might be to become more aware and understanding, more loving and compassionate, or healthier, stronger, and more skillful. Or it might be for the benefit of a friend, a cause-or even yourself.
DON'T bring pagers or cell phones to class. Leave socializing and business outside the studio, so the peace of the practice is not disturbed.
DO be quiet. It's great to share a class with people you know, but it can be distracting to yourself and others to have an extended or loud conversation.
DO bring a towel or your own mat if you sweat a lot, and arrive clean and free of scents that might distract or offend others.
DON'T push it. Instead of trying to go as deeply or completely into a pose as others might be able to do, do what you can without straining or injuring yourself. You'll go farther faster if you take a loving attitude toward yourself and work from where you are, not from where you think you should be.
DO pick up and neatly put away any props you use. If you sweat profusely please clean up your area after class with a towel.
DO take time afterwards to think about what you did in class, so you can retain what you learned. Review the poses you practiced, and note any instructions that particularly made sense. Even if you remember just one thing from each class, you'll soon have a lot of information that can deepen your own personal practice.
DO keep valuables (other than you and your mat!) at home or in your trunk.