One indicator, ready position with both hands on the racket....
Conti grip and Eastern grip, racket face is vertical, perpendicular to the ground.
SW grip, racketface is facing about 45 degrees downwards.
Full W, racketface likes to face horizontally dowward, parallel to the ground.
A player can, thru his arm, force the racket to face differently, of course.
My ready position, strong SW, lay's the racketface facing down at around 15 degrees from dead flat to the ground. Of course, I can force it to face beyond straight down at the ground to almost vertical, but it's a strain.