Now you are ready for animating, but don't know where to start. Some basics include timing, acting, lip sync, and gags. One thing not taught in any animation book I know of is how to animate mouths in clay, so I will try to explain basic mouth construction for animation. You start by roughing in the features of your characters head. The next step is to hollow out a deep hole where the mouth will be. Also, if you have white teeth on a green character, it will look funny as the white clay slowly turns green from the lips around it. So make the upper teeth from painted hardening clay. One trick is to take the color clay that your characters face is made of, and mix a piece of it with a darker color and place it in the back of the mouth before adding lips to your hollowed out face. It looks more natural, and causes the lips to stand out a little better. Lastly, add lips over the teeth.
When you animate the lips, a common practice is to cut a wedge shaped piece of clay out of the upper lip, and close the gap by moving the lip edge up to close the gap. This keeps the lip from getting a strobe effect because you don't have to re-sculpt the lip edge for every movement. And when you sculpt the mouth in the shape of an "O", you add clay to edge of the lips outward. When you change shape back to a normal mouth position, you cut off the outstretched lips carefully, so you can reuse them for the next "O" shaped lips in your animation sequence.
One last trick to animate the lower jaw moving downward, just like when real people talk. To do this, cut a line straight back from the center area of the lips, straight back to under the ears, and pull the jaw down. Then cover over the slits on both sides of the cheeks with a thin blanket of clay that you have smoothed out, right up to the lip area. It works quite nicely, and gives a more loose effect to animate the jaw of your character.