First things first, research and then designs.
The robot looks to me like he is made from lots of T.V's put together, so I researched different T.V's and robots before I started drawing.

I have chosen to alway have a picture of the original drawing of the robot on my hand in sheets, so that I am constantly reminded not to stray too much from the original design.

 I only drew six designs because I felt if I continued to draw more they would become very different and not resemble the original drawing at all.