"Before embarking on important undertakings, sit quietly, calm your senses and thoughts, and meditate deeply. You will then be guided by the great creative power of Spirit." ∼ Paramahansa Yogananda
Education in Yoga... First, consider this:
I welcome your desire and interest in taking the necessary steps to pass on the message of yoga to others. The world has many professions and careers full of people getting ahead but only a few sincere individuals dedicated to focusing on inner growth, with a desire to help others.
Becoming a teacher involves much more than just doing a course and getting a yoga certification. It requires your full commitment, a deep interest and a sense of duty, and the discipline to continue and grow in your practice. Without these, teaching becomes a job and not a vocation, and you will fail to communicate to your students the true message of yoga.
What does it mean to teach? What kind of responsibility does it involve? What is yoga anyway? Hopefully these are some of the questions you've been probing, as well as the practical side of achieving yoga certification. The first thing you should look at is your own practice. How committed are you? How regularly do you practice? What is your practice? Patanjali clearly outlines in Yoga Sutra 1.14 what it takes to be successful in your practice: do it for a long time, without interruption (i.e., continuous), and with full sincerity.
Being able to move your body into various positions is certainly a good starting point, but it is secondary to inner work. Contemplate, therefore, Patanjali's three points and integrate them into the foundation of your practice. Out of this will grow your grounding and ability to teach.
Deciding to teach yoga should not be a career move. It should be nothing less than a calling. So sit and meditate and listen to where this desire is coming from. Discover its truth, and then I urge you to resolutely move forward. This you have to do. Believe and have faith. Once on the path, surrender is key.
This requires faith but yields untold rewards and immense inner growth and satisfaction, the true seat of comfort and security. So be open to transformation and letting go. Your life will blossom, and you will be in a place to offer the teachings. Even when teaching Asana, the deeper the experience is within you, the stronger the message you impart. Even just your words and vibration can help people progress in poses (and more!).
Dedication to practice is the beginning of the journey. This dedication is more important than how "good" you are in Asana. Just commit, follow the steps, and allow it to happen. (In other words, practice, focus, and surrender.)