Just start by drawing him out in a front view and a side view and then break his body down into simplified shapes (i.e., his head looks like a cylinder with half a shere on top, and his body is a cylinder -- there, I did it for you!
). get out your 1/2 inch sheet foam rubber, cut out a rectangle and glue it into a cylinder. cut out 8 triangles and glue them together to make a half-sphere, then glue that to the top of the cylinder to make the head. Then you pretty much make the rest up as you go along.
Hope that answers your question, but it would help if you were a little more specific -- a LOT goes into making a puppet.