squash and stretch is used with "moving pictures" it makes moving objects look highly realistic, for example a bouncing ball, if you have a regular ball moving in a circular motion it doesnt look natural, but when you use the principle squash and stretch it looks like and actual ball being bounced off walls. All it does is squishes the animated figure and stretchs it.
2. ANTICIPATION
Anticipation is when your expecting something to happen or your preparing for an action to come about.
1.The preperation for the action
2.the action
3.the termination of the action.
3. STAGING
Staging is when you can tell a characters emotion, reations or what they are doing, and it should all relate to its story, camera shots can help with that as well, for example if you were to do a close up shot it could relate to an emotion such as sad or lonely or something like that. and you dont want to use too many actions in one shot, you might confuse your audience.
4. STRAIGHT AHEAD AND POSE TO POSE ANIMATION
straight ahead animation starts with the first drawing all the way through to your last. using this method you can lose size, volume and proportions but they are also controlled better this way, and fast wild actions can occur using this principle.