The cartoon effect in After Effects is great for a banner, a photographic image or video providing a simple way to give an other worldly look to your subject. It is also easy to create a 'French impressionist' look with bright colors and exaggerated texture and features. Fortunately the cartoon effect is quite easy to apply, very easy to experiment with. Like any animation or special effect, giving some thought to what your finished product is going to say, how you want it to look is a great start. A comic effect is typical for the animated helper but it is just as easy to create a little drama with bold features and shadows. Picture the Hulk or Superman.
Why not a Picasso incarnation?. These exaggerated colors and lines of definition, texture that you can touch can be ingredients for expressive emotion and 'super reality'. When you apply cartoon you have three 'high level' render options: fill, edges, or a blend of the two. These choices are just what they sound like. The edges will highlight an outline of your video in black and white. It reminds me of a black and white charcoal sketch with white fill, dark grey and black outlines. This is an extreme cartoon and while it might serve in a logo or symbol, I doubt this is what you will want for your expressive video.
The fill option does the opposite. It exaggerates only the fill portion doing nothing to the edges. Imagine puffy fill with soft textures and because you haven't used the edges attribute, edges are very rounded and reveal curves. With fill chosen you see shadowing and darker shades highlight the fill creating the cartoon effect in this fashion. There is no better subject for the cartoon effect than a human being complete with face color, lines, and texture and the clothes we humans wear. This 'fill only' approach, creates the true comic book cartoon likeness with shading and color describing human features and clothing fabric.
To get a different and perhaps the preferred cartoon effect, use these two together combining fill and edges under your render option. You will see an immediate profound difference. You see the soft textures, colors, the fabric you can touch, but you also see powerful dark lines outlining everything from your human subject to the objects that share the video. If your subject is sitting in a chair, for example, your subject and the chair share powerful outline and animated description, sharing similar descriptions providing a seamlessness to the entire image.
Remember that because the cartoon effect has graduated settings, you can use After Effects 'brainstorm' tool to get help producing some random combinations of the available settings, assisting you discovering that 'certain look' you are looking for. As you use 'brainstorm', you are presented with different combinations of the settings introduced in this article. Clicking on the ones you like will include them in a second 'brainstorm' random creation. You also have the option to add one of the 'brainstorms' presented to your current composition or save it as an entirely new composition.
Of all the effects that will help you achieve the preconceived image you are seeking, cartoon is a worthy assistant but cartoon will do much more. Cartoon will give flight to your imagination taking you to new visions you have never seen before. Enjoy!