As a tonal painter, I employ an impressionistic approach where no sketching or preliminary lines are drawn and detail is kept to a minimum. Most artists "draw first and paint later." With this method, paint is applied directly to the canvas paying strict attention to its tonal value, and hard lines are only added as finishing touches, if necessary. As a result, proportion and perspective are no longer a problem and occurs automatically.
My primary goal is to capture the light and shadow of an image in a manner that is realistic but also impressionistic in nature. Details are mostly avoided as the brain will fill in what the eye thinks it sees. As a result, you may find the painting you are looking at will force you to step back to a proper viewing distance which will render a softer, more harmonious image.