Here is the finished sketch.  Examine the next ten drawings to see the steps that were involved in creating this drawing.  Notice the lightly drawn lines that represent the axis of the body.  This drawing was done with a Papermate™ ink pen.  It was not exactly intended to be a finished work of art but is one of hundreds of sketches that I do for relaxation or for development of ideas.   Sketch often and continually.  Not everything that you do will become a major work of art but you will surely learn from everything that you do. 

I like to use ink pens when doing non-serious sketches because of the demands put upon me for control.  I am not allowed to erase mistakes so I learn to make every stroke count.  You will note that I am able to control the pen to make my lines light or heavy.  You should likewise have even better control with a pencil.  When I plan on doing a piece that will become a fine work of art, I always use a pencil unless the medium of the picture suggests otherwise.  You will find sketching with anything from crayons to chalk, pencil, or ink.