A lot can be said with a shift in expression. A change in mood, a sudden thought, a devious plan. As writers we know what our characters are feeling, but showing those emotions is often easier said than done.
It’s easy to fall on those simple words he was surprised or the dog scared her, but if the context of the story is done well, you shouldn’t need to utter the actual emotion; the facial tics should do it for you.
I’m sure you can recall a time in your life when the look on someone’s face said more than words ever could. The next time you’re facing a scene when the weight of the world rests on your MC’s shoulders and he, and he alone, has the formula that will save the world, use the memory of that real moment to describe how he looks.
Do you have any tricks for describing emotion?