Continually remind beginners of simple alignment fundamentals and proper posture.
Maintaining proper posture is necessary for safety and proper muscle toning. Beginners will not know fundamentals so you will have to continually remind them of proper basic posture tips. Quite often your regular students will need reminded of basic fundamentals for yoga postures such as toes pointing forward, knee above the ankle, depending on the pose. So keep your alignment tips basic and simple for the first few instructions of a pose or movement.
Learn each of these tips in more detail during the course and testing.
Teaching Beginners Yoga