Cover and Query letters are the key to getting noticed by agents and editors, who read hundreds of queries every day. After all, if you can't write one page well, how could you write a whole book? A query letter must have a punch to entice the agent or editor to want to want to read your manuscript now. It should be three, possibly four paragraphs and no longer. Make every word count! And don't write a form letter, every agent and publishing house are different with likes and dislikes and your query should be tailored to reflect those. So step one to writing a good query letter is research! Either do your own, or go to my Agents Page and have me do it for you. Some agents prefer quirky and new, so your letter should emphasize that. Some prefer literary to genre or commercial fiction, so you'll emphasize character arcs and personality traits. All agents have a limited number of genres that they'll represent. Do your research and submit to the right people. And do not ever address an email "Dear Agent," or "To Whom it May Concern," you've done the research and you know to whom you're writing. Use their name. "Dear Sara," "Dear Eddie," or "Dear Jennifer," are going to make you look less amateurish from the start.
Your first paragraph should include your name, book genre, book title and word count, and a logline. A logline is one sentence that accurately conveys what the core of your story is about, using your story or character arc as a guide. Ask yourself, "What is my story about?" and then answer the question. A logline, also called a hook, is not a tagline. It is not "One woman's journey," anywhere or "Only the fastest survive." If you have read The House of Sand and Fog, here is the logline they used:"When Massoud Amir Behrani, a former colonel in the Iranian military, sinks his remaining funds into a house he buys at auction, he unwittingly puts himself and his family on a trajectory to disaster; the house once belonged to Kathy Nicolo, a self-destructive alcoholic, who engages in legal, then personal confrontation to get it back."
Bridges of Madison County used this: "When Robert Kincaid drives through the heat and dust of an Iowa summer and turns into Francesca Johnson's farm lane looking for directions, the world-class photographer and the Iowa farm wife are joined in an experience that will haunt them forever." Both of these are using the "When" formula. When this specific event happens, your main character-insert short character description-does this action which causes these results or conflict, they have to overcome in their own way or these things happen. Sure, it's a formula, but it works. But it's a common formula so you may want to use it a starting point.
Paragraph two is your plot synopsis. Don't be fooled- you don't have to give away the ending. Expand on your book, and here is where you can emphasize (but not exaggerate) the parts of your manuscript to specific agents. Give more information about your characters and conflicts and the way they are changed. Specify the setting. Read the back covers of your favorite novels and try to copy how they're written, including hinting at the climax without giving anything important away. You can do this. Sit down and write it, get it all out, then edit, trim, revise and reshape into something amazing.
The third paragraph is much easier. It's about you, and you know you. Keep it short and related to writing. Don't talk about your day job unless it's relevant to your manuscript. If you're a police officer and you've written a detective thriller, that's relevant. Education is important, but again, only include it if it's relevant. If you have a PhD in Psychology and your main character has a mental disorder, that counts. Otherwise leave it out. Do include any writing you have gotten paid for or writing awards and contests you've won. Don't include comments from other people on your writing unless those people are published authors. Your mother, significant other, friends, teachers, boss, etc. do not count. If you haven't been published before, say that and also say that you're working on your next novel. You did the research so you're already submitting to agents who work with first time authors, but agents don't like one-and-done clients.
The last paragraph should do two things. You thank the agent for their time and consideration, and you specify that your manuscript is complete. As in fully written and edited to the best of your ability. Agents who like your query want to read your book, not wait for you to finish it. Never query agents until your manuscript is done. Then sign off, and you have a query letter!
Cover Letters are different in only a few areas. You still need the same format as a query, but you'll be sending it to a department within a publishing house instead of to a specific person. Unless you've met an editor at a convention and they agreed to look at your material (lucky!). The second paragraph synopsis then will include your entire plot with the climax and conclusion, and it is all right if these are a little longer. Three or four sentences, maybe. And study submissions guidelines here, too. Some publishing houses only want the cover letter and the first three chapters of your manuscript. If you send them the whole thing, they'll toss it because you didn't pay attention to the guidelines. Other houses want a cover letter, a three page summary of your book including all plot points, and then the first 50 pages. So again I say, DO YOUR RESEARCH. Don't pay postage for something they're going to throw out.
And after you submit, be prepared to wait. Most agents will get back to you in 4-6 weeks. Publishing houses are closer to 4-6 months. Take a deep breath, and work on your next book. This is the best time to start on your next project, because once you've been picked up by a publishing house, they'll want you to drop everything to make a page of editing changes in the next week, and then promote and market yourself heavily once the book is out. So get going!