The irony is that one piece of advice that was cited as basic was "Read widely," but two panelists had a long session of discussing how many aspiring writers need to read widely, Read outside the genre you want to get more ideas and notions.
The editor is not the enemy. One panelist told how she managed to get published because of one specific reject, that told her the story fell apart at the end, which made him sad. It dawned on her that the editor was not a mean gatekeeper you had to trick, but someone who really wanted her stories to be good.
One writer talked of her long struggle with exposition. Beta readers were ever so useful in pointing out where she was not clear. You need to make things clear for the reader and not dismiss the problems. (I must observe that every so often, it may be necessary to decide that someone is -- not part of your target audience. But that is a decision not to be made lightly.) And the great struggle between weighing down the story with exposition and leaving things unclear -- she oscillates back and forth, trying to hit the sweet spot.
About beta readers, they pointed out that a beta reader is very unlikely to have the correct solution to your problem. But very likely to be correct that there is a problem. Especially if several agree.
Ambiguity is not confusion. Things can be clearly ambiguous.
A in media res opening does not mean that you start with the climax, and then flash back to two days earlier when he was brushing teeth. You start when interesting thing start to happen, the day the world changed. . . . (I must confess to having horribly broken this advice. Twice. And then gone and sold the stories. Aren't I a terrible example?)
One panelist wished for having known of the three-act plot, how at each quarter of the way through, the character has to learn that his goal was wrong, or ill-advised, or pursued by a foolish means, and he has to change it. S
Some discussion of how outlining may help form a story.