How do you figure out the benefit of a mistake—knowing what to do the next time?
• Do an experiment.
• Do it where it's comfortable.
• Do it so there's no need for artistry.
• Do a little experiment.
Break a larger issue down into smaller pieces.
• Document what you did.
Take written notes, of course.
And, take visual notes.
For example, if you're experimenting with lights, step back and take a picture of the scene of your experiment.
Then you'll know where the lights were placed.
• Limit the variables.
You can determine what's happening, or not happening, more easily.
• Let it rest for a day or two.
When you come back to the mistake, you may have figured it out in the meantime.