Principles of animation

Squash and stretch- Exaggeration, the illusion of weight which can be applied to both body parts and expression. The purpose of which is to give a sense of weight and flexibility to drawn objects. In realistic animation, however, the most important aspect of this principle is the fact that an object's volume does not change when squashed or stretched

Anticipation is used to prepare the audience for an action, and to make the action appear more realistic. The technique can also be used for less physical actions, such as a character looking off-screen to anticipate someone's arrival, or attention focusing on an object that a character is about to pick up

Exaggeration-  Exaggeration is an effect especially useful for animation, as perfect imitation of reality can look static and dull in cartoons.The level of exaggeration depends on whether one seeks realism or a particular style, like a caricature or the style of an artist

Staging - This principle is akin to staging as it is known in theatre and film. Its purpose is to direct the audience's attention, and make it clear what is of greatest importance in a scene. This can be done by various means, such as the placement of a character in the frame, the use of light and shadow, and the angle and position of the camera

Timing- Establishes mood and emotion, the more frames the smoother it is. Timing refers to the number of drawings or frames for a given action, which translates to the speed of the action on film

Arcs- All actions follow a path, gravity is a force within the animation world that can be highlighted through the use of arcs.  Shapes on a set path curve in a way that introduces a sense of realism. Most natural action tends to follow an arched trajectory, and animation should adhere to this principle by following implied "arcs" for greater realism. This can apply to a limb moving by rotating a joint, or a thrown object moving along a parabolic trajectory. The exception is mechanical movement, which typically moves in straight lines

Slow in Slow out - The movement of the human body, and most other objects, needs time to accelerate and slow down. For this reason, animation looks more realistic if it has more drawings near the beginning and end of an action, emphasizing the extreme poses, and fewer in the middle

Solid drawing- reproduction of life which also generates a realism. The principle of solid drawing means taking into account forms in three-dimensional space, giving them volume and weight.

Appeal- Appeal in a cartoon character corresponds to what would be called charisma in an actor.A character who is appealing is not necessarily sympathetic – villains or monsters can also be appealing – the important thing is that the viewer feels the character is real and interesting

Follow through and overlapping action "Follow through" means that separate parts of a body will continue moving after the character has stopped. "Overlapping action" is the tendency for parts of the body to move at different rates (an arm will move on different timing of the head and so on). 

Secondary action- To incorporate secondary actions to make the world feel more organic and real, so whilst the main plot point are the expression and the words the secondary action could be background body movement which really helps to establish the world and the worlds particular set of rules.