I read somewhere—perhaps it was “5 Tips to Instantly Up Your Instagram Game” or some such—that, when taking photos of people, you should ask them to open their mouths as wide as possible.
Interestingly, it works. It seems weird, both to them and to you, but the photos that result often have much more life in them than they would otherwise.
I received similar instructions many years ago from a CBC Radio producer: I was going into the studio to record a commentary, and she advised me to make my points so emphatically as to appear (to myself) to be raving. It was very hard to do this, and it made me very uncomfortable, but I had to agree that the result was better.
An interesting piece of photography advice… I like the caricature advice for audio as well. It was something that obviously worked for people like Rush Limbaugh and Bill O’Reilly.