Body language and dialogue play equal roles in communication. Sign language interpreters are engaging and expressive. While their hands sculpt meaning for the hearing impaired, their facial expressions drive home the emotional tenor. As a public official reads from a prepared disaster statement in calm tones, the interpreter punctuates the message with sharp movements and facial expressions that convey the true seriousness of the situation.
Body Language
When writing dialogue, channel the sign language interpreter. 
Have your characters jab with intensity and sway as if buffeted by hurricane force winds. Display emotion not only in facial expression, but with shoulders, posture, gaze. Imagine you are observing your character from across a crowded room. What do you see? Are their shoulders inching up around their ears or down and relaxed? Is their erect posture tense, or loose? Are they standing close as if sharing an intimate moment or perhaps gesticulating with staccato movements. Where are they looking? Directly at their companion? At the floor? Furtively scanning the room as if planning an escape? You can enrich a scene with body language.
Have you ever been told when you were discouraged to keep your chin up? That one small action can change your outlook. Try it out on your characters. It’s rarely immediate, but lifting one’s chin gives an air of confidence and people will change the way they interact with your character. When others see confidence, your character will begin to see it in themself. How about the expression don’t slouch? By throwing shoulders back and keeping your head up (another common expression), you can improve your character’s emotional state.
Facial Expression
While our characters may be keeping their chin up, we most often convey 
emotion with facial expressions. The sad character’s lips pout, the angry character creases their brow. The problem is, facial expressions can be faked. We’ve all seen the insincere smile, the supposed contrition of a forced apology, the wounded look designed to instill guilt. But a closer look will reveal the lie. Happy eyes sparkle. Apologists peer into the offended’s eyes seeking redemption. The truly wounded drop their head and avoid eye contact.
In Conclusion
Fear, contempt, disgust, sadness, anger, happiness, and surprise are the seven basic emotions. Play with body language and dialogue to showcase your character’s emotions and motivations. Here are two helpful websites: facial expressions and 7 emotions, and sad body language.
