After you practice drawing animals for awhile (stick figures, bones, muscles, and shading cubes, spheres and cylinders) you are ready to try drawing  fantasy creatures from your imagination.  Watch this great video I found on the internet demonstrating drawing a fantasy creature.  It  is done using photoshop on the computer.  But you can draw it just as well with a pencil and paper (and you could add color with colored pencils).  This artist really knows well the bones, muscles, and structure of animals!