My Process

Firstly i would draw the character.

Then i would use my light-box to trace the drawings 12 times in pencil. 

Then i would lightly erase the pencil markings.

On six of the sheets the outline was drawn in oil pastel, on the other six sheets the fill was drawn in marker.

Once scanned the images would be brought into Adobe After Effects. 

The images are then edited. This is done separately for the Fill Layer and the Line Layer. Then they are combined.

They are cut to a sixth of a second in length in a minute long composition.

"This composition is known as fill 1".

Then a new composition is made of the right length of the scene.

This is known as "fill 2"

"Fill 1" is placed into "fill 2" as many times as necessary. In this case it was 3 times

Next i make a new composition called "fill 3". In "fill 3" I place "fill 2"

This mean that i can now edit "fill 2" in it's entirety. I now apply the extract keying effect removing the white from the scene.

After one has repeated this process with the related line layer, it is time to unite them. 

When both layers are present I invert the fill layer. 

Now it's time to place the figure in the scene. 

I change the levels of brightness and contract on the man. 

The background is created by applying liquid Fractal Noise effect to a solid layer in a composition then bringing that composition in and turning it into a Overlay layer and applied to a water coloured page. This same is done for the sky just it is a gas fractal noise effect. These layers are angled to give a feel of depth.  Contrast and brightness levels have also been changed. 

The end product winds up looking like this.

For more complex scenes I would draw the limbs separately.