The most common query error is . . .

Starting out without knowing what you're doing. Writers tend to forget that once they’ve polished their manuscript and begin contacting agents, they’re making a major shift from “telling” to “selling.” From this point on the query must be written in terms of the recipient, i.e., the agent. What does an agent want to know? Their #1 question is, “What’s in it for me?” Does the writer have a saleable manuscript, and can they write? An agent can determine this after reading a few sentences. Obviously, if you want your query to be read, spend some time learning how to write it so the query showcases you and your project in a structured, professional, AND interesting manner.