As a fan of Lovecraft, I try to be as faithful as possible to his descriptions.
When designing the Mi-Go, one of the most iconic of the Cthulhu Mythos monsters, I went for the original text:
“They were pinkish things about five feet long; with crustaceous bodies bearing vast pairs of dorsal fins or membraneous wings and several sets of articulated limbs and with a sort of convoluted ellipsoid, covered with multitudes of very short antennae, where a head would ordinarily be (…) a sort of huge, light-red crab with many pairs of legs and with two great bat-like wings in the middle of the back. They sometimes walked on all their legs, and sometimes on the hindmost pair only, using the others to convey large objects of indeterminate nature (…) It was a great crab with a lot of pyramided fleshy rings or knots of thick, ropy stuff covered with feelers where a man’s head would be.”
His descriptions are what makes his creatures so unique. Deliberately vague and mysterious.
Designing it is also a big challenge. With so many great artists and designs out there, it is becoming harder and harder to come with fresh ideas and solutions. What I found most difficult was staying within the crab description and not going for the lobster direction.
Another important part of the creature, as we never see them in the text, is a footprint. I was puzzled for some years how this description would translate visually:
“It was not a very deep or fresh print, but seemed to be about the size of an average man’s foot. From a central pad, pairs of saw-toothed nippers projected in opposite directions”
The wings also proved interesting to solve. It needed to be able to fly, so they needed to be big, as they were going to carry a crabby-thing, and also fold correctly.
And here is the final rendered version of my design.