Place ideally one real coffee can before you on the table and make sure it is well illuminated. Reflections help the object, and later your drawing, look more vivid and interesting.
Alternatively, you can also use a photo as a drawing template.Draw the outline of the coffee can on the watercolour paper with warm grey V 274. Then work out the surfaces with warm grey II 271 and warm grey V 274. Do not apply any paint to your drawing in places where the surroundings are reflected in the porcelain. Apply somewhat thicker outlines to the drawing with warm grey V 274.