Start with a slightly pointed semi-circle facing the direction your shark is heading
Add a big fin at the top by drawing a curved upside down V shape. Then draw a smaller curved V shape at the bottom to make another fin.
Draw a couple of lines from each fin to make up the rest of the shark's body. Again, make them ever so slightly curved to give it that bottle neck look.
Connect the two lines of the body with a wide W on its side
Add a squashed circle to the head and a big coloured circle inside that to help the shark see in the murky depths of the ocean
Draw a curved line from the point of the nose. Don't forget to add a couple of sharp teeth by drawing some triangles from the mouth.
Finally, add three lines just behind the eye so your shark can breathe underwater. Feel free to also add extra features like battle scars or a hat!