Here are some useful tips to improve the avatar quality.
If you move a lot when capturing the visemes and other images, the avatar may become unnatural. If you want to create a qualified avatar, keep staying at the same position during the avatar creation process.
Sometimes one or two images seems weird comparing to other images. In this case, you can modify the specific image at avatar detail page. At dashboard, click the avatar to go to an avatar detail page and then click the "Modify" button for the target image.
The avatar reacts to the sound received from the microphone. So sometimes the avatar reacts to noise and echo sounds other persons' talking. For preventing the issue, wea a headset when you use the avatar.
Virtual Backgrounds will smooth your avatar movements and make them more natural.