Eyes are 3 dimentional.
Don't move head and eye at the same time.
When you watch a character you always watch the eyes.
Blink: When action is off screen you can have characters on the screen blink intermittently will add to film and character (some slowly blinks an older character. faster for younger)
Long holds, character can breathe. Only when you have plenty of time and it should be slow, not panting.
Inhaling and exhaling must be at least 2 seconds.
Secondary character should never compete with the main character.
When repeating characters walking into distance they have to diminish in size enough to relate to sharp perspective. Otherwise the characters will give a feeling of growing larger.
Older: slow long step
Child: short quick steps twice as fast
Exaggerate differences. You have to exaggerate in animation twice as much to show your action twice as fast. And in doing this you will learn to correct walking
Two legs should meet in body. Legs should always be the same length.
You have to feel the spine of body.
Drunk: off balance
A child will have more effort and will take twice as long because he will have to put both feet on steps before proceeding to next.