
Send a query letter via postal mail or e-mail, but don't include attachments unless requested.
I respond to simpler letters that focus on the narrative and tone of the book, with some author background. If it's too slick or complicated, I tend to turn off to it. I don't mind multiple submissions but generally don't answer any that are clearly cattle calls.
Links:
[1] http://www.fletcherandco.com
[2] mailto:christy@fletcherandco.com
[3] http://www.pw.org/literary_agents