As someone who makes a habit or a living out of assuming different characters from time to time, it's important to work on the canvas (yourself out of character/costume/make-up) and experiment to see what you can do that you haven't tried before or could do better than the last try.
Models in particular- and I always forget this- if you hope to get better at posing and using your face/body to express very different moods, PRACTICE. Make faces in front of a mirror, photograph or record yourself moving/walking/talking/posing, find a model whose style you like and try and recreate their poses as practice.
Check this colour change from the after a few hours at the beach ;P
What do you guys think, should I do a video tutorial on my minimal make-up and skin/hair prep for taking polaroid pictures? Let me know in the comments and don't forget to subscribe to my YouTube channel for all kinds of cool stuff coming (and already there).