Sketching prepares for all other work and alows one to study the subject in
various ways, for instance: finding shapes, notan structures, connecting lines, and noting colour vibrations. By observing and responding with quick gestures one becomes aware of possible compositions and relationships that can be called upon in abstraction.
Here are some examples of studying the Galiano Coastline before painting.
Rock formations photographed and sketched can be comparisions.
Cropping the subject and adding form may be a further exploration of a subject, as well as using various media such as pen, pencil, watercolour or acrylic. Playing with values and line while grasping an overall placement of shapes in a quick gestural way is one way to train intuition. This takes little time and can become a regular practice if one keeps a sketchbook handy.