The Spin Dial
Here is a succinct, wonderful article on forehand spin variations from my teaching colleague and good friend Weston Reese. We've looked in detail at the windshield wiper finish and how it relates to spin many times. (Click Here for one presentation of that.)
That work has focused primarily on the forward swing and followthrough. In this article Weston shows you how to set all that up by focusing on the backswing and the angle of the racket face. He also explains how it applies across the range of forehand grips. I like it a lot!