Yoga requires regularity. To build a stable mind and body and to create a strong foundation we recommend attending at least 2-3 classes a week (but ideally not less than once a week). The most important thing is practicing regularly with your teacher and also practicing on your own based on what you have learnt in class.
Of course we understand that beginners will not have the same impetus as a seasoned practictioner. Therefore it helps to be systematic, be attentive and alert in class, note sequences down after class and work systematically using them. Working little things, one at a time, will give more openness of mind to overcome the fear and resistance to practice alone.