Queries are so important. They are your enterance into the editor/agents world. So, this is how I write one.
Generically speaking- I begin with why I chose that particular agent/editor. I like to mention something personal. Perhaps I read their blog or met them at a conference.
Next I make my pitch. Hopefully a snazzy three sentence or so synopsis of my work with a hook to draw in the reader.
I'll follow with a the title, genre, word count and age range for my work, trying not to sound robotic.
My personal info comes last. If you have any writing credits this is where you put them. I wish I had some! So, I just mention my college degree and the fact that I'm a member of the SCBWI.
To end your query I think it's important to thank the agent/editor for their time. From what I've read from blogs, agents/editors go through 50-100 queries a day!
Always send a self addressed stamped envelope. Well, if you want to hear back anyway. If your emailing they usually just email back a response. Ta Da, all done.
I tried being fancy with my first book query. I sent out invitations welcoming editors to the world in which my manuscript took place. That bombed. I also tried being exact and to the point, but I think that's a little too dry. I read one agent's blog that said they didn't like short and choppy. They wanted things to flow. So instead of writing- My middle grade story is 50,000 words. Try something like; my middle grade fiction story of 50,000 words mixes horror into the teen world of drugs and abuse. Make it flow, they want to know you're a good writer. I'll let you know if that worked when responses start coming in lol.