ok...ok...(bodyits)

I know theres about a billion or so threads on making a bodykit, but i still dont understand the concept of the plastic sheets. Are you supposed to build a rectangle and shape it down or trim and then glue? And also I've tried putty and have failed many times. I've used orange bondo, tamiya smooth, testors and squadron(both). All without even a half assed decent look. What else could I try to get this to work...this is the only thing holding my skills back for modeling.

Styrene is attached to the body to get the basic shapes and outline then the puty is used to do the final shaping and to fill it out.
Try Eurosoft Glaze Coat its a very fine grained Bondo type filler that works very well, very little shrinkage and feathers nicely