Show your characters’ moods well and how they change. After all we’re not in one state of mind all the time so neither should they be. Moods affect actions affect consequences and plot! Show your characters learning from their experiences - what not to do again for example - and where appropriate where a character refuses to learn. Look at why they have that refusal - is it just stubbornness or are they afraid of change? Have they good reasons to be afraid?
Show your characters’ expressions. I tend to get Eileen to grimace a lot (!) (though to be fair she does have cause) and am aware I need to vary her expressions. Also show your characters trying to hide what they really feel - after all we do it so why shouldn’t your creations? What happens when a character fails to hide how they feel or shows their emotions to the wrong person? What catastrophes could be unleashed?