What really jumped out at me in Chapter 3 were the array of different file formats and their uses. X3D and VRML for use in interactive 3D environments like multi-player web games. Then there ate OBJ and DXF universal formats for transferring files between different 3D programs. Chapter 4 provides a description of the polygons, lines, and techniques we use to model. I hadn't learned about sweepin before and I'm curious to try it. Sweeping moves a 2D model along a predefined path in 3D space to generate a complex object. I found the section on using lattices for global deformations quite helpful. The emphasis from both chapters seems to be on planning your projects destination before you begin and keeping a good record of your polygon count. There were some cheats to keep polygon count down. Having models with lower polygon counts or level of detail, to replace the originals as they move away from the camera. Also using "billboards" for backgrounds with few polygons and a projected image map can save rendering time.
There are some useful things at the books website, artof3d.com