At my previous job; BE Intent, we had a a little studio setup (courtesy of Samantha Haehae my insanely awesome co-designer and photographer). It was actually the best, when we asked people to come in and model for us. We'd start rolling people in for half hour slots the entire day with next-to no breaks. Our brief was to capture various people's facial expressions through different states-of-mind, each model was asked to display emotions from one extreme to the other, eg. happy - sad, relaxed - stressed, tired - energetic.
Sam's been my photography mentor and thanks to her, this is what some of my shots came out like. I didn't feel the need to do much post, as I wanted to savour the essence of capturing and reflecting the natural human, being transparent with their emotions. Experimenting with gels was a highlight.