Sombra

O site de uma marca de canetinhas para desenho, a Copic Markers - The markers created for creative people, tem uma sessão de tutoriais para pintura com as canetinhas. Pra quem está no Básico-Médio, é bem interessante. Há dicas desde sombreamento simples, com cores e tom-sobre-tom, até aquele com "risquinhos" (textura), mais profissional.
Na galeria do site, há muitos desenhos coloridos apenas com os marcadores da marca, que dão até vontade de sair pintando.
Pena ser tudo em inglês, embora não seja um inglês complicado.  Vale a pena visitar.

Segue os links e um trecho de um dos tutoriais.

Um Beijo!

TUTORIAIS
http://www.copicmarker.com/tutorials
GALERIA
http://www.copicmarker.com/category/gallery

"Basic Shadows with a Cube

Here is an example of shading using cubes. Cubes are great objects for practicing shading. They can be simple, or complex, depending on the composition.
In compositions, light usually travels in a straight line. Any object blocking the light will block it in a straight line.

The side of a cube that is closest to the light will be the lightest. However, we need to show a slight color difference between the top and the side. In this case, the front is colored lighter than the top, showing the light is strongest from the front.
Next, think about the shadow that the box casts on the ground. The object will cast a shadow shaped like itself. The corner points out, so we have a pointed shadow.

The edges closes to the front will catch more light. Add highlights with Opaque White, or a white colored pencil along the front edge. In real life, the shape would not have black lines defining the edges, so this strong highlight along the edges is very important."