When I teach my classes I always begin by doing a demo of the subject I am trying to teach. Here are two of them:
Whenever I do a still life I light the subject with a lamp so I’ll have shadow and light. I draw the scene on the canvas. I draw each shape I see, like the shapes of shadows or of light. For example, I draw the shadowed areas of the bananas, then the lighted areas. Once the drawing is in, I begin painting. When I paint I don’t think “I’m painting a banana”, instead I think “that shadow shape has a blue tint to it,” so I’ll paint that. Then I might think “there is a blue-green shape” and I’ll paint it, instead of thinking I’m painting the edge of a plate. The cloth is white, but with the yellow light shining on it I put a yellowish tint. If you think about it, my process is like putting together a puzzle: I paint shapes and colors and they eventually come together as a picture.
Here is another class demonstration:
I’ve done some cars driving past the Indiana State Capitol building. I use linear perspective. There is a vanishing point around the left-center of the picture. The road comes from that point – the left side comes almost straight down and the right side is nearly horizontal. The cars are drawn in the same way with their left and right lines. You also see them driving up the street using atmospheric perspective. The closer cars are bigger and more detailed while the ones further up the road are smaller with very little detail. You will note the sunlight on the right side of the capitol dome and the yellowish tint on the road. These things, as well as the color of the sky and the shadows on the ground, suggest it is late afternoon.