Thank you to
storm_grant for this list of how to query agents from Janet Reid (Literary Agent) and which blows away most of which we know - I particularly like number five;
5. Write what you don't know. I recently attended a panel sponsored by the New York Chapter of Mystery Writers of America, and it was interesting to me that five of the six authors had created a protagonist in their own image. That's all well and good, but I'm much more interested in the people I don't see every day. The one author who mentioned her protagonist was a Pakistani terrorist was the author I went out and bought the next day.