WEIGHT DISTRIBUTION

One key advantage of a geared head is that it divorces your mass from the camera’s movement. In the event of the dolly coming to a sudden stop, your body may want to continue down the track. As long as the gear head wheels don’t turn, though, the camera won’t follow your body. This can be more difficult with a fluid head, but it’s definitely possible if you can distribute and brace your weight through three points of contact with the dolly. If you’re sitting, plant your feet firmly, or find a comfortable sitting position, and then put your upper body weight onto your left hand, which should be placed somewhere near the camera (around the base of the fluid head, or the boom arm itself). The idea is that your weight is firmly planted between your legs and that hand resting on the dolly, leaving your panning hand free to operate the camera.
This works in a standing position as well, where your weight is spread out between your legs and your left arm. The right arm, controlling the camera, can do what it wants.
Over time you’ll learn to completely divorce your panning arm from the movements of your body. I’ve gotten to the point where I can operate a 180-degree or greater move on a fluid head while climbing over a dolly. My body does one thing while my panning arm does another.