Assume starting off with no (or minimal) hip rotation using standard unit turn.
I don't know if I am getting hip rotation on my forehand, and I have no camera with which to check. I can easily focus on getting plenty of shoulder turn into the shot, but I don't see using the hips as being nearly as easy and comfortable.
The only things I have found are
1) Sit and lift. Makes sense. Using this method, the legs can easily power shoulder rotation.
Using the vertical life down through the shoulder as the center of rotation, using the rest of the body to hit the ball by rotating about that axis.
Is it always necessary to use a lot of hip rotation on bigger forehands? I notice that on some shots (high drives), Federer doesn't rotate his hips as much (from what I can see). Also, it's not possible to rotate on every shot (running forehands being a prime example), which would sap some power away and force the arm and shoulders to produce the power instead, which is I guess why we want our opponents on the run (so they can't set up and use their hips to unload their best shots on us).
Main question is what are some tips to incorporate or improve/increase the hip rotation on the forehand (or groundstrokes in general).