POINT 2: GET SOME DETAILS RIGHT
Hair and fur are especially difficult to create in the correct scale for a micro piece, but can be very persuasive toward overall “rightness” if you manage to do it. Sometimes, also, you can fake it a little—if you get some significant aspect of a furry piece really right, you may be able to get away with less accurate scale for the hair or fur.
Such as, specifically: if you get the shape or “gesture” right for the whole piece, or get the texture or color detail for the fur/hair really right, the less-than-accurate scale may seem visually unimportant.
For example, Lucky the little white dog does not really have fuzz, he has beautiful little swirls of fur. But the piece captures pretty well some aspects of his typical pose—he’s alert, friendly, smiling, and with a perky little standup tail—and so the fur on his micro-crochet piece is suggestive enough of reality to be convincing while you’re focusing on his overall look.
An even better example, however, is the little Shih Tzu from @obscurelysmall. As far as I can tell, this piece uses single strands of embroidery thread (like the well-known thread from @dmc sold in six-strand bundled skeins) as hair. The strands are not further separated into plies. You could actually count the strands in the photo, so clearly they are much thicker than actual dog fur strands would be. But the shape of the piece is great and the color detail is amazing, including the black “face mask” commonly seen in this breed. In other words, the facets of the appearance that ARE accurate are persuasive enough to make the thicker-than-strict-scale fur strands acceptable—in fact you may not even notice their thickness while you’re admiring the lovely colors.