Shark fin too thin and jagged like a knife

Hello. It's easier to watch Kent do it on the lesson than to explain it by text. When Kent is sculpting the shark, you'll see him use a mix of inflate and smooth, sometimes inflate, scrape, smooth. The idea being creating a "meaty" surface by inflating and then taking away the excess. But again, it's so much understandable if you see him do thought it.

One super important thing to keep in mind, Kent is a master sculptor and he makes it look easy, as if you just have to follow the steps like in box modeling and you'll get the same result. But in sculpting is more like watching someone draw a realistic portrait with pen and paper and then you picking up the pen and paper and trying to do the same, you're not going to make a realistic portrait just because you saw someone else do it. Same with sculpting, it takes a lot of practice to get that meaty feel on your sculpt.