Back to the SCBWI-LA conference and some pet peeves and comments that editors on a panel spoke about.

Submissions and guidelines – Some writers do not follow follow publishers’ guidelines.
Packages sent in by some writers are not professional (especially the synopsis).
Some writers do not do their market research and have no idea what is out there. Is what the writer sending in tie in with something else already out there? Is it unique? Tell how.
Some query letters that come in have no personality. Editors want to see who the author is on that page. Put some of yourself into the letter.
Slush pile – Nowadays, most editors only respond if interested.
The relationship between the editor and the author is a big part of the process.
Voice is what a lot of editors look for. A good hook and a great plot as well.
Before sending in submissions, research, research, research the market.