Her advice -- the short version.
Send queries Tuesday thru Thursday during regular business hours. They get way too much sent over the weekends and your work could get lost in the shuffle.
Don’t bother sending queries in August or December. They are too busy to deal with them.
Tailor your query to show that you did some research about what the agent likes to represent.
Some reasons she says no to queries:
Bad writing in the query letter (Hey, if you can’t write a query what are the odds on your book?)
Sounds like a public service announcement
Inappropriate to YA
Some reasons she said yes:
Writing style in the query
Do not start with a What if question in your query. Without exception all agents at the conference say they hate this technique.
What new query advice do you have?