Ah, you’re asking about the ever-elusive perfect query letter. Glad to hear you’ve already tucked away your cerise stationary for another time. There are whole books devoted to query letters, if you care to look them up.
The best advice I can give you is first to be sure you know that the editor you’re sending the letter to works on the type of book you are trying to sell her. Get her name and title right in the address. Call the publisher’s switchboard and check if you need to. Then write a BRIEF and BUSINESSLIKE letter. Try for one page, two maximum.
Introduce yourself, mention if you’ve met her at a conference, had an appointment with her, or if she asked for material from you. Give your writing credentials including contests you’ve entered, or better yet, placed in or won. Tell her what you do for a living if it gives you credibility as a writer. You might mention that you’ve been reading romances/her particular line of romances and are familiar with the genre/series requirements.
Tell her the title of your book and whether it is finished or not. Then tell her about your story. This is the hardest part. You need to tell the story briefly – in about three to five sentences. Seven tops. That means you tell about your heroine, your hero, the conflict and the setting. (Master this skill. You’ll end up doing this a million times in your career as you explain your book to everyone from editors to reporters to the person who stops by your table during a book signing.)
As you put this description together, think about the selling points for your book, the things that will lure readers. Be as specific as possible. In PAINTED BY THE SUN, for example I would mention that the heroine is a PHOTOGRAPHER traveling through the Old West LOOKING FOR HER SON, who was mistakenly sent west on one of the ORPHAN TRAINS. The hero is a COLORADO TERRITORIAL JUDGE who… (Caps added for emphasis.) And so on. In the last paragraph tell the editor what action you want her to take. If you want to ship her a proposal, tell her that. If it is requested material, tell her you are looking forward to her reaction to your synopsis/chapters/ whatever. I’d stop short of telling her I was looking forward to having her buy my book; that sounds pushy. Or just tell her you hope she enjoys your submission.
Remember that the query letter is a sell piece. It should be your very best writing, snappy, upbeat, and most of all clear. Include your very best ideas, polished until they shine, but don’t be cute. Use standard business letter format, a standard type, and good grade business paper in a neutral color with an envelope to match.
Once the query is printed out, seal it, and get it in the mail. Once it’s gone, don’t second guess yourself. It may not be the perfect query letter, but it was the best you could do at the time. Then prepare to be patient. Answers from agents and publishers can take awhile.
If you don’t hear anything from a letter, send another in about six weeks. If you sent requested material, and you haven’t heard anything in about eight to twelve weeks, call and check on it. Just ask for the status; they should be able to tell you without it being a big deal.
As for things not to do — well, I would avoid telling an editor how much my mother likes my work. I would refrain from telling her how much I write like Julie Garwood.. (Editors like to discover that stuff on their own.) And I probably wouldn’t ask if that grape punch I spilled all over her at the last conference came out of her ivory lace dress.