Anyone who has used 3d Studio Max and then switched to Maya has always missed the use of Smoothing Groups. While Maya doesn't have Smoothing Groups, with a little bit of planning and work, we can achieve the same result for our low polygon models. We're gonna start off by modeling a quick and low polygon space helmet. Start off by making a sphere. Click on the option box next to Create/Polygon Primitives/Sphere and set your subdivision axis and height both to 12.
Rotate the sphere 90 degrees on the Z axis. Select three rows of faces on the front of your helmet. Stop your selection leaving a few columns on the left and right side unselected.
Activate the extrude tool.
Keep your extrude tool in the local mode and move the faces in on the Z axis.