Teaching yoga can be both rewarding and relaxing. The important part is to prepare yourself before your first lesson. Learning about teaching online yoga sessions is something that should begin within your own practice.
More than Asanas
Yoga is a holistic practice that encompasses much more than just the physical movements. Even if you never incorporate the other aspects of yoga into your personal classes you should be aware of them. There are eight limbs to yoga. The positions are just a single aspect.
The first limb is Yama, or the universal mortality. The second limb is Niyama, your personal observances. The third limb is Asanas. This is the physical part of yoga that most know. The fourth limb is Pranayama, the breath of life. These are also practiced in many online yoga sessions. The fifth limb is Pratyahara, the control of your senses. The sixth limb is Dharana, the cultivation of your inner awareness. The seventh limb is Dhyana, one's meditation on the Divine forces. The eight and last limb is Samadhi, your individual connection with the Divine.
Read a little on the other limbs of the practice. Be knowledgeable about the historical and cultural important of the practice. It won't seem to be knowledge that is useful in day-to-day teaching. This is not the case. You will have students ask questions about the practice. You will also find the deeper understanding helps you in your own teaching.