My criteria:
So, I figure that I have plenty of time to craft the most amazing cover letter possible for my book (since it's not finished yet) and then carpet the earth with query letters. Yes, many of them say "no simultaneous queries," but if I have a manuscript that I spent three years on, I don't want to send it off to one agent, wait two to six months, send it to another agent, etc. A good fisherman uses a sturdy pole and the right bait. A REALLY good fisherman uses four or five poles and homemade bait. A professional uses half a ton of chum and a big fucking net.