Animation of moving lips help please!

Hey, I’m making some kind of postcard where some famous videogamehero wishes you a mery christmas. The lips, almost the only part moving, are a problem. I can’t get a nice movement like you see in the attached file. I’ve used a shape tween.

All the lines are in one layer, so do I have to put them all in different layers or something?

Thank you very much!
Tipsko