I'm planning on shooting a short film in about 2 weeks with my Nikon d5300. Since its aAutofocus is unusable for video (it's great for photos, but too slow to be used for video in live view), I decided to manually focus. There will be many close-up shots (i.e. the actor's face, maybe a bit of the shoulders) with a shallow depth of field (up to f/1.8, 35mm). Often, the distance to the subject will vary throughout the shot as there will be camera movement.
So I figured I need to practice manual focussing. How? Do I simply take an object, record a video, move the camera and try to keep in in focus? Do you have any other tips?
I still did not get to shoot the short film as planning didn't go as expected and then, I had a lot of stress with school. However, the answers so far are great in that they explain how MF is usually done on a higher budget. I still however miss how I can practice focussing manually.