Advice on Writing Query Letters

The Top Ten Query Mistakes
http://cba-ramblings.blogspot.com/2010/02/top-ten-query-mistakes.html

What You Need Before Your Query
http://jetreidliterary.blogspot.com/2010/01/what-you-need-before-you-query.html

The Batch Querying Theory
http://blog.nathanbransford.com/2010/02/batch-querying-theory.html

Querying When You’ve Written a Trilogy
http://bookendslitagency.blogspot.com/2010/01/writing-series-and-trilogies.html

Non-Fiction Book Proposals
http://bookendslitagency.blogspot.com/2009/01/what-is-book-proposal-for-nonfiction.html

Query Shark: How To Write Query Letters…or really, how to revise query letters so they actually work
http://queryshark.blogspot.com/