Then you can also create a texture effect. Just cover the drawing with a light stroke first then follow with rough, think strokes to serve as details . texture. This can also be applied when you're using colored pencils. And you can also create a light, smooth look with crayons. Just color your drawing with very rough and thick strokes (this might make the drawing look messy at first) then rub off the excess color with cotton or scratch paper.
A few years ago, I wrote a book about realistic crayon drawings. What a joy it was to create, for I had brought my childhood dream into my adult professional life. I wanted to share it with others, for few knew that crayons are actually a wonderful fine art medium. They're not just for kids!