Old masters developed a thorough working method that helped them visualize scenes from history and mythology. Sixteenth century painter Federico Barocci (1528-1612) planned his paintings with a series of eight steps, according to his biographer, Bellori.
1. After deciding on his idea for a picture, Barocci made dozens of loose sketches to work out the gesture and arrangement of the figures.
2. He then made studies in charcoal or pastel from live models.
3. Next he sculpted miniature figurines in wax or clay, each draped in tiny costumes to see how they would look under various lighting arrangements.
4. He proceeded with a compositional study in gouache or oil, considering the overall pattern of light and shade.
5. With that completed he produced a full-size tonal study or “cartoon” in pastels or charcoal and powdered gesso.
6. He then transferred this drawing to the canvas.
7. But before proceeding with the painting he produced small oil studies to establish the color relationships “so that all the colours should be concordant and unified among themselves without hurting each other.”
8. Then he went ahead with the finished painting.
Barocci may have been more meticulous than some of his contemporaries, but his process was not unusual, and virtually every artist followed at least some of these steps. He was a big inspiration to Rubens and many others who followed after.
These basic steps have been followed all through the history of imaginative picturemaking, right down to William Bouguereau, Norman Rockwell, and Dean Cornwell.
Wikipedia entry on Barocci, link.
Computer wallpaper, link.