In keeping with our theme of making a mess, get to the model into a state that you like as quickly as possible. You have to see what you're making before you can revise it.
  Remember though, the efficiency rules still apply.  If you can't spin your model around, your going to miss critical mistakes that you won't catch until its actually been animated.  Make a mess, but keep it clean.
  As for the basics of sculpting, there are only two qualities that truly define your model. The silhouettes of the contour lines.
  As you sculpt, move the camera around as much as you can, inspecting how the model looks from all different angles.  As you find incorrect silhouettes, fix them.  When you can't find anymore... you're done.
 
 

The edge loop
 
When modeling the moving organic form, it is critical that you give yourself the control curves that will let you best manipulate silhouette and contour.  After animating your creation you find that a particular pattern works best, I call it an edge loop (see figA)
  An edge loop closely mimics how real muscles work,  and if built correctly, will  give you control over contour and silhouette in any position.
  A useful by-product of using edge loops is an extremely efficient (rendering wise) model.  It is also the best way to control the subdivision surface when smoothing an object.
  Think of edge loops as laying a series of rubber bands over an entire body, adding extra bands where you need more detail (e.g., around the mouth and eyes) and fewer where less detail is needed (e.g., the back of the head).
 

  Finally, study shadows of people and animals to look for inspiration about where to place your control curves.