What: Drawing the subject in black, white, and grey before colour, focusing on light and shadow.
Why: A painting succeeds or fails by its values before its colours; values build volume and depth.
How: Reduce the scene to 3–5 values, set one light source, and distribute light and shadow clearly.
Common mistake: Jumping to colour before building values, so the work looks flat.
Exercise: Draw a value study of an apple in three values only before colouring it.