We draw at first one potato which we see completely.
Then the second, which behind the first potato.
Then draw small bow-shaped curves in certain places, as shown in the picture. It everything, drawing of potatoes is ready.
It is possible to shade and shade still it, thus small curves can disappear too therefore once again put them as in the previous step.
Take a rubber (eraser) and make patches of light from light, but not too light, slightly touch paper with a rubber.