Remember the fundamentals
While animating your scene refer to the 12 Fundamentals of Animation I mentioned in the introduction. Using exaggeration, and squash and stretch, in your poses will enhance the feeling of emotion. Likewise, incorporating anticipation and overlapping action into your drawings will give your scene a sense of life. Using these in combination will give your scene a sense that it’s grounded in reality.
When animating a dialogue scene, don’t overdo it. Creating a mouth shape for every syllable is a common mistake that makes animation feel unnatural. Focus on the key sounds, major vowels and hard consonants. And create mouth poses a few frames before the sound. If you study speech in slow motion you’ll see our mouth starts forming shapes of words before we hear them.