From the treasure hoard of ConceptArt, a brief guide to "How To Draw Sharks" by Waterbird.
I'm linking to this not from an overwhelming desire to draw sharks (though God knows, sharks are Friggin' Cool, Man!), but because I found it an exceptionally well-done combo of art and writing. Waterbird's authorial "voice" is engaging and informal, but the guidance is informative, succinct, and easy-to-follow.
This is how to "how-to" a subject.