How do you pronounce “Cthulhu”?
I was working on a post on that topic for this blog. But in my research, I found an article in Crypt of Cthulhu #9 (1982) which says it much better than I ever could. You can read the article here, and you should — it’s great fun, and very interesting.
The bottom line is that opinions vary, and even Lovecraft himself seemed to change his mind. More on that in the article, of course.
And how is Cthulhu really supposed to look? Obviously there are differing representations; many of them are extremely good. But as it happens, Lovecraft himself drew Cthulhu (below). (Joe Broers has created a sculpture based on that drawing — buy it here, if you wish.)
My opinion? That there is no right way to pronounce Cthulhu or draw him. Lovecraft didn’t really intend to create a universe where anything was definitive. So in my opinion, the “correct” way to draw or pronounce Cthulhu is… whatever works best for your story or your art!