Dagon (Character creating)

As I need to draw the characters in this book I first need to understand every aspect of their features, movement and behaviour. Here are all the descriptions of the Dagon H.P Lovecraft gives in the short story when looking at carvings of the creatures;

• ''enormous size'' 
• ''I think that these things were supposed to depict men—at least, a certain sort of men; though the creatures were shown disporting like fishes in the waters of some marine grotto''
• ''Grotesque beyond the imagination'' 
• ''they were damnably human in general outline despite webbed hands and feet, shockingly wide and flabby lips, glassy, bulging eyes, and other features less pleasant to recall.'' 
• ''chiselled badly out of proportion with their scenic background; for one of the creatures was shewn in the act of killing a whale represented as but little larger than himself''
• ''grotesqueness and strange size''

Where Lovecraft writes ''other features less pleasant to recall'' I see this as a chance to add many features as I like to the creature, I want to look in to adding features such as tentacles, sharp teeth, pincers etc. 

Below is an extract from the book that describes the Dagon, but this time the description is written when the main character witness's the creature first hand instead of in a carving;

''Then suddenly I saw it. With only a slight churning to mark its rise to the surface, the thing slid into view above the dark waters. Vast, Polyphemus-like, and loathsome, it darted like a stupendous monster of nightmares to the monolith, about which it flung its gigantic scaly arms, the while it bowed its hideous head and gave vent to certain measured sounds.''

My next step is to start sketching ideas to create the creature, I am going to start drawing each feature step by step until I am happy with each aspect then I will put the features together and play around until I come to a final idea.