Another thing I have noticed recently... do you have your head to tell a story? do you know that at least 90 to 80% of our communication is done non-verbally i.e body language. That is heaps of body cues, micro expressions, and general posture that we as animators are able to communicate to a our audience.
The first we look at humans, is straight at their faces, we try to seek out eye contact although then we move on to their nose or mouth to avoid staring at them straight in the eyes, which we find extremely uncomfortable .. (unless we are trying to avoid them altogether by averting our gaze and turning our bodies away from them). but the usual the pattern we create is this one:
So most of our first impression as well as when the person is talking, is of this triangle, although when you get in a more of personal relationship, you maintain eye contact with them longer and for an increased period and the triangle that you create with your eyes becomes longer taking in the whole torso.
Timing is important in this endeavour, if you make your blinks or your eye movement too slow the audience will wonder if your character is half asleep or just not quite there. The eyes are a tracking tool, defining movement, making out shapes. Try to watch someone's eyes, the eyes stop for a couples of seconds and then with nearly like a "flick" they are moved again. Blinks are when the brain is trying to process the information, or to keep the eyes moist and to protect them from harm. In some cases when someone is extremely stressed or tired the blinks become longer as the brain is trying to give the body a "rest" from the world.
The normal human emphasises their speech with their heads, it curious to watch but it is so much fun to watch someone's head to bob and weave to what they are saying. Sometimes they have subtle head shakes and head nods like they themselves are disagreeing or agreeing on what subject that they are talking about.
The head leans to the side or toward the speaker if the subject is quite interesting to them, you can tell if it is not, the head remains in the straight up and down or propped up with a elbow, this also works while someone is talking on a telephone although the person is not there. The head if one the hands is close to it, the head will lean in that particular direction if it is trying to support the body language that the rest of the body is giving off.
The head also can show the "positive" or the "negative" of the characters thoughts, if sad or depressed the head as well as the rest of the body slumped like they cannot or don't have enough energy to support themselves, the head might be nearly resting on their chest if it is "nearly the end of their world" and the head might drag, timing wise behind the body movement.
Angry the head is nearly in a straight up and down position, it is going to react like the rest of the body in a "choppy" movement like the body is a blade trying to hack away whatever's is bothering them, the head might do two things, lead if the person is really lost it (I suggest running really fast) or be constrained in movement, if the person is trying to control their temper.
Happy or in Love (just think of "singing in the rain, you get the picture), the head will be trying to levitate the rest of the body closer to the sky, it will be turned upwards and it will be trying to lead the rest of the body, the body will be dragging the body behind it and you could do some really nice work with feet nearly on tip -toe with the vitality that the character is feeling.
Now... I think I have done enough, writing, animators don't do well with reading, they like pictures. But before I finish. Still remember that there is the rest of the body to animate and that is going to support what head is trying to tell the audience, also know that people after they look at the character's head are going to take in the rest of the body, be warned.