One editor opened with observing how often he has to tell the author to throw out the first portion - - the first chatper if it's a book, the first few pages if it's a short. Start where the story starts. The purpose of the first page is get them to read the second page. It's not a place for info-dumping, but for intriguing.
Don't take rejection personally. It's just a story that's getting rejected. Any personal comments are a wonderful sign of hope. Most works are rejected on the first five pages, and a large percentage, on the very first page.
I observed that it's one thing to take hope from them, and another to assume that they are right. Whereupon the panelists took it and ran with the main issue, which is that when push comes to shove, the editor doesn't get the byline, the writer gets the byline, and if it's your name on it. . .
Hmm. . . I think this blurred with another panel, of which you shall hear more shortly.
Though, come to think of it, this was the one where we were warned about public controversy causing problems, a la Orson Scott Card.
And how you should be working on your next work when submitting the first, so you don't have to knock one out in six months after having slaved over one for five years.