Hierarchy or levels

With any sort of design its helpful to have a hierarchy of details, so that you have broad areas or the overall shape thats readable and then details or parts that  have their own structure but don't disrupt the whole.  Again some creatures have a purposely cryptic pattern to disrupt the outline or disguise themselves, but often when designing a character or creature you don't want pattern or detail to upstage the part of the character its applied to so that you can't see it or "read" it.There might be a key feature you want to draw people's attention or focus to, which is hopefully readable in the silhouette , but also having detail or contrast with adjacent areas  can help draw attention to things.