DISCLAIMER! My dad and little sister have read, I think, every Kat Richardson book currently out in paperback. They love the books. I, sadly (~weeps~), haven't read them yet because my to-read pile is a tottering hazard.
Plus, with this post, I've totally caught up with myself.
[I have decided, using my stuffy head-cold as an excuse, to be silly here. Please accept all of the above as truthful and deliberately exaggerated and silly.]
Urban fantasy writer, Kat Richardson, posts about Acquiring an Agent on her blog. It's long, but detailed and comprehensive, and basically, some overall good advice for writers currently editing, or just about to begin querying agents. And of course, the usual disclaimer--this is her opinion, based on her experience, and everyone who reads it has to look at it through that understanding. Besides that, it's a good read, IMHO.