When performing beginner yoga poses, it's important to concentrate on each movement. Remember that you are connecting the body with the mind and the breath. If you experience pain, release the hold slightly or exit the pose. Technique and form is more important than attaining the pose. It is better to perform a posture correctly one time rather than repeating it incorrectly. Keep to the order of the poses as given by the instructor - they are taught in the order that will best benefit your practice.