Art works, including 3D sculptures and 2D advertisements, are already abstracted and serving as excellent sources to practice drawing.
Unique faces, beautiful or ugly, are easier to draw, because they already have distinctive features. It is the mundane and ordinary that take will more efforts to read, see, extract, and depict.
I ensured correct proportion of the base layer/structure before proceeding to the details. This saved time, taking me about one hour to finish this one. Previously, I sometimes noticed mistakes on the base layer which thought I could fix or hide with upper detailed layers, but that just took me a lot of time with little benefits.