Sketch out the basic circles and then connect the curves.
Erase the inside circles leaving the basic outline of the shapes.
Start to fill in the eyes, nose and other details.
Fill in the rest of the other details like the wrinkles and fold in the skin to provide depth.
Color and contour the manatee. Remember to color in the larger base color of middle grey all over, then add the white or light grey highlights and then the dark grey and black areas.
This tutorial is excerpted with permission from <a href="http://amzn.to/1lspJ00">"How to Draw Incredible Ocean Animals"</a> by Kristen McCurry (Author), Jared Osterhold (Illustrator), Smithsonian Institution (Contributor), Inc. Wilkinson Studios (Contributor) and published by the Smithsonian.