Light

Art is Nature speeded up and God slowed down. -Chazal

A crucial element in painting is the consideration of the light source in your composition. Unless you're into surrealism, the light source should be consistent for every element in your painting. Lighting may come from the side, back, top, front or it may be diffused as in an overcast day. One way to become familiar with the effects of your light source is to set up a still life, such as a bowl of fruit. Shine a lamp on it from different angles and notice the different results. Notice where the shadows fall and where the highlights are. Pay attention to the effect on color. Make sketches and notations about the light source. Look at the outside world and note things such as time of day and weather conditions and how these affect your visual perception, and the mood of the scene.