When animating a character, you frequently run into a case where you're trying to animate a secondary detail on the character as he's moving. For these situations, I like to create a new camera and parent it to the character. This way, the camera goes anywhere the character does. I find this approach helpful for facial animation on a moving character. To lock a camera to your animated character, use the following steps:
Now, wherever the head goes and whichever direction it turns, the camera is always looking at your character's face.