Anyway, the first panel I went to was on Character Building.
One panelist described how you would have a character in a play, and not only would the play-goer have a list of dramatis personae, he would have the character as he walked out on. And you could see how he looked, which would tell you a lot about him. One audience member later said that it really annoyed her when a character gets a description later that contradicts, and I pointed out some authors don't describe at all; in his Lost Fleet and Paul Sinclair series, over a dozen books, John Hemry/Jack Campbell describes one character, once, because she has green hair. Much depends on the point of view character, and what he would notice.
Another one talked about the importance of what the character is doing when they arrive on the scene for the first time. It has to be a revealing, an indicative moment. (I didn't get to point out at the time that you can summarize on the page as you can't on the stage, but even there, describing a character's typical actions are )
On the other hand, you may, and probably do, want to reveal more about the character as the story goes on.
The grave important of motive Pushing a little old lady is very different based on whether you are trying to push her into or out of the way of a car.
How they say things. You want to watch out for the adjectives, but a panelist read a passage from Mark Twain given the same line of dialog got entirely different meaning based on the imputed tone and body language. (Twain thought interviews were problematic.
Contradictions in character are realistic, but you have to fit them together. One panelist propounded -- James Two-shoes walks five miles through the snow to give someone the change he had forgotten, and on the way kills Little Red Riding Hood and steals her basket. And then he went hmmm, I could do something like that. I pointed out it was classic sociopath behavior because the murder was hidden. And the panelist riffed on it being the need to be seen as good, only. And then we went the other way
They talked about murderers. One had only the highest and noblest motives for murder -- like, I must reunite the war-torn country. The other had somewhat baser motives but still convincing yourself it's a good act. I observed that most murderers manage by not thinking about the morality of the matter, only the practicalities. One panelist thought it a cop-out. Me, I thought that the panelists were devising ways that they would commit murder and so revealing why they aren't murderers; what's really a cop-out is ignoring the actual motives of actual murderers.