John compared how visual effects were made for movies from the 1950s with contemporary movies. He showed clips from Disney's 20,000 Leagues Under the Sea and clips from Pirates of the Caribbean.
The process hasn't changed that much. You start off looking at the script, have discussions with director, and decide what needs to be shot using visual effects: anything you can't just go out and shoot, anything that doesn't exist, anything that's too expensive, too dangerous, or just not possible.
20,000 Leagues Under the Sea used miniature ships in a studio tank (about 200 ' x 200', a few feet deep). The last pictures that used this techniques was Tora! Tora! Tora!. The tank method works pretty well but the scale of the water doesn't work well. Droplet size is wrong.
For Pirates, Knoll also built a tank, but came up with ways to split in full-size water droplets. Adding full scale water in background really helps.