But how do you tell what's important enough to shoot first?

Well, that's up to you, but it should be relatively easy. If you did your job in pre-production, chances are you've basically watched your film in your head. During any given scene, which shots are the ones that make up the bulk of the scene? Usually there are a handful of shots that are used most, and those are the ones to focus on.

For example, if you're shooting a basic dialogue scene, you'd want to schedule your OTS (Over The Shoulder) Medium Shots first, followed by your Medium Close Ups and your Master.

Then, towards the end of the day, you'd pick up your inserts, exteriors, reaction shots, cutaways, and the other little bits and pieces that will make the story shine. Plus, you could build up additional coverage of the scene to give the editor even more options.

But no matter what you do with the latter part of the day, you'll be able to rest easier knowing that no matter what happens, you have the basic building blocks of your scene.

Of course, you won't always be able to do things exactly this way. Maybe you only have a key actor or location during the second half of the day. But even then, prioritize wisely and capture your most essential shots quickly.