Using charcoal and pastels have drawbacks in that smudging is a real problem when drawing. Working on the image, being right handed, I start at the top LH area and slowly make my way down the sheet. Initial laying out of the subject features is critical: eyes, nose and mouth positioning within the face if the drawing is a portrait. I try and choose subjects that are a challenge, like drawing blonde hair on white paper! Adding a little colour to a black and white image can also give it a different dynamic.